uxzeq3e4 UOTIETpPeY eUUSZUY ET-NdW/NY
uc}ION JO UOTINGTAISTG eATFETHUND

xo = q31100 ‘xe@ot-e = aitos

79339K3 3w1a 30 %

atas 008

teorte a1ud eee2 ~ (Zu) O344

@30339X3 3WId JO % *SA WHE NIBH O1 3A110798 aa
NABL1bd UNNBINY WOLLSTivLs

*CT-¥ oanbya

er oot

ui0;7ed UOTZETPEY euUEZUY S-ysY
yore u0T Jo uoyanqyzqsTa eATZeTRUMD

%@1-0 © G3i10d ‘xeO1-e = ar70s

Tesese iva = se9tez BMIL eL2t = (ZMK) O3M4

(30339X3 GWIL 40 % "SA WH3d NIBH OL 3A11734% aa
NB3L10d ONNSINY TWITASTibIS

“9T-W ornbpa

wooe
WIOW
o1 738

°
N
1

ata



O° O8e+ Ald’ O6°O2+

oTqeubew 09 STE F® DEIUTOd ystq ueA
SWSu HuTSn yoReq Huoy ze pernseeW ure}z}eq PUUeZUY 9-ASY YUeqang

Ald? a0°O2+

saaus3a

*z@e-w eanbtd

@0°O2-

'
'
Jeeeuuz

dqeoesbone

etozez BWIL = szsese Jivd
Gr 2z- * waaay 34071904
2°9l- = 39Ny3Au 34073018
Z'9z- = 39vyaAv JLatdHOo

$33493a

“SA Wad

“MH34iUd UNNGINY YoaUe

torg =

1622 =

(MEd) 9INOd ASE

(93S) a0laad

(2H) AONANO3H4

eo*es-

wo3a

NIBH
o1 138
yanod

aaoy ol

Ata,
B60°S+

eoa's+


Ose

Ald? 00°O2+

oTIeUbeN of LE Fe PeRUTOa YSTa UPA SWSY
Hutsn yoeeg Huot ze pernseew ure;z}ed euUSzUY P-NdO/N¥ SO}TWeTY SOT

yess

Ald’ o0°0z+

*6@-W eanbtg

SEECEEL! eeias=

eo" os-

CLELS
NIOW
O1 134
yanod
daoa

Alas
e0e'sSr

esztet

2 er-
St yz-
z*or-

3HI1L 62S0S2 3lva
= 39va3AH 340710E
= 39va3AH J407R0TS
= 39¥y3AU 314374N09

$33493aa

“SA waa

*HYGLLUd UNNGLNY Ybabe

eee'sSr

6°6e- = (HEC) YINOd AVA
s2te = (938)d018ad
S'tes2 = (ZHN)AINaNODad

A-37


UPA SWSU 5UTSN SYN BpeweTY 7e peinseaw ureqQzeq eUuUaqUY J-YSW PUeTXeO

“OTIOUBEW OOZT Ie pEeqWTod YSTa

‘9€-W eanbT gy

est 6

‘ : : : i jaa os-

--di}...| nuaa

NIUW

. _.. or aaa

yanog

aAay

: aq @
zezSyt 3WIL = 2ttise 3iva 2 N31 @ 3dbL
S33493d "SA @d@ ‘NY3LLbd BNNGLNY avaUa

e76e- = 39baRAN 3a07NIbE 2°tt- = (Wad) y3M0d Awad
e*de- = 39uaaAu 3a07R0TS 2t% = (938)00T43d
9°8e- = 39VARAW 31374dN09 zzez = (2HW)AON|NDIaS

A-46


UTeD weequTeH PEISN(pY POIeUTISA wy
aTbuy juewornsvey

tt*c=0 LU°Z@=0 ze°e=0 LL*t=0 8°t=0 SNTd eTbuy 3ITL 20J uyeo weequyeW peysnfpy sepntour »
secét-att | se*t-=t | 90°L-=1 svecen [se*tt-="
lctt- O°t- a*6- Tet uror- Sve ost ve GG-Ked SLAVEL
O*bT- ore- z*et- s*0- o°vt- wx" 6T oss ze et-rav HOW:
£ S*e- e°s- S*0- e°ST- ¥4S "2% ze NOLUOr:
vra- BC+ ad “oad oe'l+ $°L- weGe ore te yrido SOLINITY SOT
e°tt- vee T°e- o°T+ L°0t- 89° SL°e ve s-usv HOWda SNOT
$*OT- cto+ e°e- Bot o'ot-" elt s‘e be S-usy oravire
6°It- 0°0 9°8- O'vt o°tt- #G°le s°€ ve 9-UuSY wkKYauNne
z°et- o*e- T6- O's+ s*ST- wl S'e ve L-usv SA1TONY SOT
(rap)
(Fae) (tap) (rap) (Fue) T3437 (tap) | (saguoga) (tap)
TWdaAgT TA5" THAIT gag) = Nwdiavd Ive TTONY NIVS
iWIGSI. wavad NVICSI. Wada} WuNaaev | WaanrM. GILL) WWAENTW!]  FUALWIONTLON
SdUTAOVE | gqotyove | AOTSGIS| BdOTAGIS NvIGad:| aqausaray| wundaiy] ‘TWNINON NaWAI OOD asva/ALID

Suvdvu ZHD 6°Z=L°2 dO SOTLSILVLS NYALIVd VNNGLNY
T-W TavL


Figure A-21. Antenna Radiation Pattern of Ontario

420 4g t7e
GAIN RELATIVE TO MAINBEAM

ASR-5 Radar Measured by the FAA

ss sé So
40
=20
sie s5
Go
ay a 7
F- \ . \ \ 80
et
+ T D0
, |
Boo / {00
250
Lio
240 ‘Yeo
zs0 130
4
2to 1Se
200 Yeo


‘oTJZOUBeN OZTE 3 HuTRUTOg ysta uPA

SWSU DUTSN META UTeZUNOW Ze perNSeeW UTEzZeq PUUSQUY L-YSY PUeTXRO ‘¢EE-Vv eANhTg

ose ost 8

Jaq os-

wud
NIM
_ pa 3a
wanod
aaa

nN
w
1

ecozs

9° 8e-
8° 9e-
6° 2e-

SWIL Elise Jivd
= 39093AN 3d07NI0E
= 39bae3AH 340730IS
= 39ba3AU 3137dH09

$33493a

"SA ad

‘NYSLUBd UNNBLNY abaUa

eUN

o°lg- =

2o7h =

ezzz =

3iiv @ 3h
(WE0)83NOd ABE
(938) a01d3d
(ZHW) AONANOAaS


oTt-

Zepey USY JO UISIQeg UOTJETpeY euUSEZUY UOTReASTA PseiNseayy

WVGENIWW KOUd SATUDAG
0 S oT st 0z

*@-v eanbtg

sz of

St

0z-

ra)
et
'

OT=

WYAENIVW OL ZAILVISY EP

w


received power measured on the 8580 spectrum analyzer. Also
during these measurements the oscilloscope on the van was
observed, and the pulses from the Ontario ASR-5 radar were
stretched out to approximately 100 usec.

Norton AN/MPN-13 - Figure A-28 shows the Norton AFB
AN/MPN-13 environmental antenna pattern measured at the Los
Alamitos radar site with the AN/CPN-4 antenna pointed at 56.5°
magnetic. The pulse train separator AS-330 was used to dis-
criminate between the Norton AFB AN/MPN-13 and the March AFB
AN/MPN-13 since both radars operate at approximately 2800 MHz.
The Norton radar was requested to operate on three stagger
(3x365 = 1095) PRF, and the March radar with stagger off
(1095 PRF). When Figure A-8 is compared with Figure A-28,
the environmental antenna pattern shows the multipathing
caused by the Chino Hills located between Los Alamitos NAS
and the Norton AFB.

Long Beach

Measurements of interferer environmental antenna patterns
were also made at the Long Beach ASR-5 radar site using both
the RSMS van dish antenna and the antenna of the ASR-5 radar.
The RSMS van dish antenna height is 14 feet, and the ASR-5
antenna height is 26 feet. The following is a discussion of
the environmental antenna patterns measured at the Long Beach
radar site.

Los Alamitos AN/CPN-4 - Figure A-29 shows the Los Alamitos
AN/CPN-4 environmental antenna pattern measured at the Long
Beach radar site with the RSMS van dish pointed at 97.4°
magnetic. A comparison of Figure A-29 with Figure A-7 (Line-
of-sight measurement) shows that the average backlobe level
is 9.7 dB lower at Long Beach indicating that the environment
is attenuating the backlobe more than the mainbeam due to
foreground clutter.

Figure A-30 shows the Los Alamitos antenna pattern measured
using the Long Beach ASR-5 antenna operating in the right-hand
circular polarization mode (same as RSMS van dish). The main-
beam to average backlobe level using the ASR-5 antenna is only
33 dB as compared to 43 dB (Figure A-29) using the RSMS van
Gish. It is difficult to resolve this difference in mainbeam
to average backlobe ratio in a multipath environment since it
is not known whether the difference in atenna height between
the RSMS van dish and the radar may have changed the average
backlobe level or the differences in the radar and van antenna
patterns caused the change of average backlobe level.

A-35


uze33ed
UOTIeTPeY BUUeZUY GS-Nda/NV dav

STAvrL JO UOFINGTAISTG SATRVTNUMD *6T-¥ eINbTa

OI-@ = G3110G ‘xoeT-0 = aII0S
@30339%3 3WIL 40 %
os °

tosz = (ZHH)O384

@30339x3 3WIL 40 % ‘SA WYRE HIBN O1 ZATLOIZY aa
NUBL10d WNNSINY WWITLSTivIS

aa es-

uz039eq UOTRUTPeY wuUeZUY ET-NdW/NV

Yore_ JO UOTINGTAISTG OEATZUTHUMD “gT-¥ eAnByd

*O1-@ = GILL0G *49eT-@ = GITOS
atay oo: §7322%3 3Mt4 40%

ooo1+

1eveSe 3iua = pStezt aMrd s'eee2 = (ZHW) 0384

303393 BIL 40 % “SA WYSE NIBH OL 3ATLHT3B
NM3L10d BNNDANY TWOLASTIBIS

ee*os-

A-21


ANTENNA RADIATION PATTERN STATISTICS

TABLE A-3

OF BURBANK ASR-6 RADAR

GAIN IN CUMULATIVE CUMULATIVE PROBABILITY

dBi (G25) BIN COUNT SUM PROBABILITY | DISTRIBUTION
(b5)
27 iL. 1 -28 +28
20 a; = 2 56 +28
25 i 3 83 -28
a uF 4 1.11 28
7 1 5 Ao: -28
4 a: 6 1.67 28
2 7 8 2.22 «55
ae 3: aly) 4.72 2.50
0 7 24 6.67 a
as 15 39 10.83 4.16
—— 27 56 15.56 4.73
os 39 95 26.39 10.83
-4 15 110 30.56 a7
as 45 155 43.06 12.50
-6 30 185 51539 8.33
-7 30 215 59.72 8.33
-8 16 231 64.17 4.45
=o 31 262 72.78 8.61
-10 14 276 76.67 3.89
ce BE 30 306 85.00 8.33
m1 6 312 86.67 1.67
IS 17 329 91.39 4.72
14 pie 340 94.44 3.05
SLs ad 351 97.50 3.06
-16 4 355 98.61 1.11
1? 3 358 99.44 83
~18 al: 359 99.72 -28
=19 1 360 100.00 -28

A-27



MUTUAL ANTENNA GAIN MODEL

Previous discussions in this appendix dealt with statis-
tical models of single antennas. However, since both the
victim and interfering antennas are rotating and both the
antennas determine the level of interference coupled into
the victim receiver, it is appropriate to determine a statis-
tical distribution of the mutual antenna gain of both antennas.
Since the probability distribution of the victim and inter-
fering antenna radiation pattern are independent, the mutual
antenna gain can be obtained by taking the convolution of
the distributions of the victim and interfering antenna
radiation patterns.

Figures A-21 and A-22 show the antenna radiation pattern
of the Ontario ASR-5 radar and Burbank ASR-6 radar respectively
measured by the FAA. Tables A-2 and A-3 show the probability
distribution and cumulative distribution of both radars
respectively. The mutual antenna gain distribution can be
obtained by forming a random variable, Gy, (Reference 19).

cc. = Gl + G2 (A-1)

Where the probability of a specific mutual antenna gain level
(G,) is given by:

P(G1j+G25 = Gr) = 2 ayy

Where: a,b, = the sum of all mutually exclusive events
where Gli + G23 = Gnr

a= Probability of Gl;

b.

j Probability of G2.

a]

Figure A-23 shows the mutual antenna gain probability distri-
bution of the two patterns shown in Figures A-21 and A-22.
The straight line of the mutual antenna gain distribution
between -8 dBi and -40 dBi indicates that the mutual antenna
gain distribution in this region is gaussian distributed.

Even though the statistical mutual antenna gain model
described in this section takes into account the line-of-sight
azimuthal radiation patterns of the victim and interfering
radars, the model is not a realistic statistical model which
can be used to predict the interfering power level received

A-23


uo 1oj}eIedeg uTerZ esSTNd pue OTZeUBeN OG°9G 7B PezUTOd euUuSsqUY P—-NdO/NW
Hutsp soytweTy SOT 7e poanseoW ur0e;}edq PUUSZUW ET-NdW/NV UOJION *QZ-W eINHTY

- sagusaa
o°eser Ald’ G6°O2+ G°OSt+ Ald+ @0°82+ @0°e7-

@e°'es-

by be CLES
NibW
-4-- OL 434
sanod
dasa

a Ala,
800"S+

ZSes9t 3WI1 = ofsese Jiva goose

S33493d *SA Wad “NASLLUd BNNGLNY auaua
€ be- = J9NHIAY BIO TAIUE 8°S9- = (HATIYINOd ABGd
8°SZ- = 39ya3Au 34073015 e6°e = (93S) d01d3d
T'@e- = 394sRAN 3137dN09 Of = (ZHH)AINSNOIYS

A-36


age

LG-USM OJUEeWRTDeS FO uUr|RZZeWd UOTRETpeY euuszUuy pPoeansesW

of JO FITL Puusquy 10zZ

est

"€T-w eanbta

Se

id oS-

Wu3@
NIBW
ol 138
Banod
aaga

Be6est BwWik gttise 3ivd ‘ @9 N31Liv @ 3dbi
S33¥930 "SA da ‘NA3LLUd UNNSINY Ybaue

9'hZ- = 39va3AW 340 7NIVE Ite = (Hdd) 83MOd ANA

€'yl- = 39vazAy 34073018 69°61 = (93S) G0Taad

6°22-

393A 3137009

2662 = (ZHW)AINSNOSAS

A-18


b-NdO/NW

o*oser Ald? oetaz+

sO}TWeTY SOT JO UTeR}eg UOTJETpeY eUUSzUY pernsesl) *L-W eandta

ornate

s33ys3q

— on'se-

waa NI
yanod
MWad

‘IZAGT Tap 0

aa3a

Atay
g00°S+

Z2°at- = NYIG3H 340719NE
86°ti- = NUIGIN 3TOITFMIS
2e°2t- = NHIG3W J197dHO9
ter2t- = 390¥3AH 31374N09

$334930

‘SA Wad

“HedLled

SUNGLNY seabe

teporee

eQo'st+

(Wad) 99NOd ABB

ge'e * (3s) dolaad

42082

(ZHH) AINANVIS

B-10


oTJeubeN COP Fe pezUTOd Ystad ueA

Bbutsn soqtweTy SOT 3e peanseeW urez}Zed euUezUY G-asY OTIeQUO *9¢-v eANbTY

$334930
he Alds 08° O2+ 63° ez-

t+ Ald? @0°O2+

00° oc-

' H Hl

‘ t - Wea

NIBH
O41 134
aanod
aaoy

aeose4-aa-4----f---

ae Alas
O0G"S+

ee0"'S+
S829rz2t Bwit S2SoSé 3ivd
S39u93d “SA Gd ‘NYSLLbd UNNGANY YuauS
s Av 34070000
aouazay T'ss-= (Wad) YaMoa Nvad

g'ee- = 39baaAN Za073GIS i9* = (ods) doruaa
s'ze- = 39¥9aAN 313746H09 ets = (zHW) AONGNOGud



measurements were made with the measurement antenna stationary
and the interferer antenna rotating.

Some measurements were also made of the peak power
received from interfering radars while rotating the RSMS
van dish. These measurements were made to document the
multipath reflections of the environment and are discussed
in the propagation Appendix D.

Los Alamitos

Measurements of interferer environmental antenna patterns
were made at the Los Alamitos AN/CPN-4 radar site using both
the RSMS van dish and the antenna of the AN/CPN-4 radar. The
RSMS van dish was approximately the same height (14 ft.) as
the antenna of the AN/CPN-4 radar. The following is a brief
discussion of interferer environmental antenna patterns
measured at the Los Alamitos radar site.

Long Beach ASR-5 - Figure A-24 shows the Long Beach ASR-5
environmental antenna pattern measured at the Los Alamitos
radar site using the RSMS van dish. A comparison of Figure A-24
with Figure A-6 (Line-of-sight-measurement) indicates that
multipath reflections were occurring from the environment.

Also the average backlobe level of the antenna pattern measured
at Los Alamitos is 5.6 dB lower. This tends to indicate that
the backlobe level is being attenuated more than the mainbeam
due to foreground clutter at the Long Beach site. This was
one of the factors contributing to not being able to observe
the predicted interference from the Long Beach ASR-5 radar.

Ontario ASR-5 - Figures A-25 and A-26 show the Ontario
ASR-5 environmental antenna pattern measured at the Los
Alamitos radar site with the RSMS van dish pointed at 35°
and 40° respectively. The Ontario ASR-5 radar is at a bearing
of 40°. A comparison of these figures with Figure A-5 shows
that there is a significant amount of multipathing occurring.
The multipathing was caused by Chino Hills between Los
Alamitos and Ontario with elevations over 2000 feet.

Figure A-27 shows the Ontario ASR-5 antenna pattern measured
at Los Alamitos using the AN/CPN-4 radar antenna pointing

at 40° magnetic. One can easily see that there is a signifi-
cant difference between Figures A-26 and A-27. The reason
for this difference is that the AN/CPN-4 antenna has only a
1.5° azimuth beamwidth as compared to the 8 degree azimuth
beamwidth of the RSMS van dish resulting in a different
spatial weighting of the multipathing signal. However, during
this set of measurements, the AN/CPN-4 antenna was aimed
between 30° - 50° magnetic with very little change in peak

A-30


g-usy xURqang Jo UOQVZed UOTJeTpeY eUUSzUY PerNsPE}; *p-y eandSta

$334930

o'osc+ ALG? OO°GZ+ O° OSt+ Ald’ G8°O2+ ea'ae-

: PRERPREESY 5 SCR SESE eS parapes ae
zZose2t anil gzsece 310d

$33993d ‘SA ad *Ne3Litd UNNILIY Ybdee

6°2e- = 39Nx7AY FIO NINA 1°82 = (Wad y3nod AYId

9°62- = 39Na7AN 34073418 eo°9 = (93S)d0la3d

ze- = 39WNIAW 31L3971dN09 1642 = (ZHWIADNINOISS

eo'as-

woad
NIOW
oL 734
aanod
qaaa

atlas
ooo"s+

o90"s+

ea


L-usv seTebuy soT jo uzezQed UoTAeTpeY euusquYy pornseey *e-v eanbhta

saauoaq

s'o8e+ Ald’ 90°Oz+ Atds oo'oz+ ao'oz-

eo os

ere Cee eer fe) es re

oes Gowe

TNT wuad
MIUH
f= = OL 13a
ygaod
adaaa

= Alas
g00"°S+

+t

z2ecet JWI 8zsece Jivd

oo0'S+

Saa49ad "SA aa NYILLYd SHNGLNe yodee
2°8e- = J9NIIAW 3d07NIVE o°2e = (NADI NINOd NYA
S*62- = 39¥a34H 340730TS eo'b = (99S)aoraad
S°9e- = 39VsZAY 4137dN09 @saz2 = (2H) AIN3NOaNS


Ur0Z}ed UOTZETPeY PUUsQUY 9-"SY UIe77ed UOTIETPeY euuezuy 4-uSY
yueqing JO UOTINGTzASTq BATZeTNUMD *sT-y sanbyg eTebuy soy JO wOTINGTIISTG SATZeTHUMD *pT-¥ eanbTg

= g3110d *xeoI-e@ = artos XOl-@ = G31100 ‘xe@t-e = a1ros
-§79339%3 guts 40 x ‘ e°eers + GPE339x3 Burs 40%

woae
NIBH
01 138

arar
eee'se

Sanahicsive Senea; aut 1628 = (ZHM) 0304 szsese jaya = zzeeet aia zsez = (ZHM) o3us :

@30339X3 3W11 40 % ‘SA WH3G NIBH OL 3ATIbIBY a G@30579X3 GWIL 40 % “SA WH3E NIbU OL BATLUI3y eo
NB3L16d BNNBINY TWITLSTAbIS NUBLLbd WNNSINY TWOTLsTuBLs


G-USW Yored Buoy yo uzeqQeq UOTIETpPeY euUSZUY perNsPoW

Ald’ 00° O2+

$a3ua3a
Ald’ 90°O2+

*g-y eanbtg

90° OS-

wuaa
Hoon
-| o1 133
aanog 9

Tap 0...

SS

eee || ee

anny ot

Atlas
o0o'S+

++------+---4---

Bse9Taz aw

Zibe- =
2:oe- =
e'ee- =

mk vesose 3iva

3SbaaAW 320 7NOUE
39bysAH J3d073G1S
39bs3AH 3131dHO9

“SA Wad WH3L1Hbd YUNNZINY ababe

2°ep

89° =

e222

(Wad) 33m0d

ooa's+

Ae

(94s) dorad

(2H) AIN3NO3H4




APPENDIX A

ANTENNA CHARACTERISTIC MODELING

INTRODUCTION

The subject matter discussed in this appendix includes
the antenna model used to predict interference in the Los
Angeles and San Francisco investigations, and the antenna
reciation pattern measurements of radars in the Los Angeles
and San Francisco areas. The measured data was compared with
previous measured data and existing models. Also discussed
in this section is a mutual antenna gain model and the inter-
relationship between antennas and environment propagation
phenomena which determine the interfering power level seen by
the victim radar. A discussion of the RSMS van system hardware
and software used to measure the radar antenna pattern charac-
teristics is given in Appendix G.

Since antennas are the means by which an interfering
signal is radiated and coupled into the victim receiver, an
adequate antenna model is an essential component in the
capability of predicting radar-to-radar interference. Because
of the dynamic nature of radar antennas (i.e., rotating and
nodding) and differences in site conditions, a statistical
description of the radar antenna radiation and reception
characteristics is a more realistic approach. The statistical
model may be represented in terms of a three level pattern
consisting of a mainbeam gain region, median sidelobe level,
and a median backlobe level; or in terms of the likelihood
that any particular level will be equaled or exceeded using
the cumulative gain distribution of the antenna characteristics.

THREE-LEVEL ANTENNA PATTERN MODEL

A three-level antenna pattern statistical model for an
average clutter area was used to predict interference in the
Los Angeles and San Francisco investigations (Reference 13
and measurements). Figure A-l shows a pictorial representa-
tion of the three-level pattern with the mainbeam, sidelobe,
and backlobe region. The statistical median antenna gain and
degrees for each of the three regions used in the Los Angeles
investigation were:


indicate a median backlobe level of -11.3 dBi (29 dBi - 40.3 dB)
for the environmental antenna pattern of the Mountain View
ASR-5 radar measured at Alameda. The median backlobe level

of -11.3 is close to the -12.85 dBi averaged median backlobe
level of measured line-of-sight antenna radiation patterns
given in Table A-l.

SUMMARY OF ANTENNA PATTERN MODELING

Line-of-sight (free space) antenna pattern measurements
made during the Los Angeles and San Francisco area investiga-
tions on cosecant squared elevation type antenna had an
averaged median sidelobe (3° to 25° and 335° to 357°) level
of -7.0 dBi and standard deviation of 3.3 dB. The average
median backlobe (25° to 335°) level was found to be -12.8 dBi
with a standard deviation of 3.1 dB. Considering the statis-
tical antenna pattern models given in References 13 and 18,
and the measured data resulting from the Los Angeles and
San Francisco measurements, it is recommended that a median
backlobe level of -13 dBi with a standard deviation of 4 dB
be used to predict radar-to-radar interference.

Environmental antenna pattern measurements of potential
interfering radars made at the victim radar site revealed
that line-of-sight (free space) antenna pattern models will
not result in realistic pulse amplitude distributions at the
victim radar RF input. There are propagation related phenomena,
such as multipath wave interference arising from multiple
scattering of the waves by mountains, buildings, and other
structures which affect the interfering signal pulse amplitude
distribution. Also in some cases, there is more attenuation
of sidelobe and backlobe levels than the mainbeam due to
foreground clutter at the radar site. The effects of these
propagation related phenomena are dependent on the antenna
positions and antenna patterns of the victim and interfering
radar antennas. Since the multipathing and foreground clutter
attenuation of the interfering signal and the antenna pattern
characteristics of the victim and interferer antennas are
statistical parameters which are difficult to separate in the
real environment, it appears that the free-space antenna
patterns could be modified to incorporate these propagation
phenomena. One particular advantage of this approach is that
it can more readily be incorporated in the present PPI simu-

lation program.

AS @ result of the Los Angeles area investigation, it
appears that potential multipathing through mountain ranges
may be identified. However, the effect of multipathing on


€I-NdW/NV YOteW FO UTSZRZEY UOTZETPeY euUSqUY peINnsee, ‘*6-y sANhTy

$7 3493u
ay oorere ao°eZ2~

— MET
aE

ooser Ald? 00° 0z+

oo'As-

CCE
Nib
oO. 134
aanod
aaoa

' 1
' 1
' ' '
ES ee eee

TAATT Tap’ o

4-12

Ala
oou's+

pstezt AWit Jesese jiva o00'S*
3334930 "SA Wad ‘HAGLIHd UNNGLNY abaue

bibe- = JOvAaAw B40 TINE e'ez = (Wad aaNOd Awad
2° le = J9v4aiy 340730TS ee" = (94S)d01a3d
S'ee- = 39AIAY 3L3I1dNOD S'aos2 = (ZHU) AININO3aS



er eser

€T-NdH/NW

Alde o0°0z+

O°aste

233993d
Ald’ oot ore

uOFION JO UXOZZeq UOCTFETpeY eUuUDszUY peInses]

*g-w eandta

go'az-

1
1

oo°Os-

nuaa
NIB
-| OL 734
4anod

0
-- ‘TaAa't

yap 0

IGAaT TAP O

] mAoa

alae
e0e's+

mee Pe

gorart

3° 6e-
2°82-
s*2e-

clbes togese 31nd
= aguaaAy 3407N9bE
= a9u43au 340730IS
= 39b4RAu 3137dN09

$33993q

“SA uaa

“N¥aLLod

BNNZING YudUa
e'ee =
bet
eosz =

O68" %+

(NEO) Y3MOd Ad

&

(93s) ao1aad

(2HM) AON3NOIaS



SWsa 5UTSQ MeTA UTeJUNOW

e9e

*OTJeUbeW O60E Fe pezUToOg ystd ue,

qe peanseaw urezQed eUUdzUY TI-NdW/NY epoweTy

“pe-w eandty

Seiraleiatae tate

Sovideowewes es

aq 6s-

wuaa
HOW
OL 13a
CELDT]
aaoa

veleet awit

6*te- ©
9° é8- ©
a S8-.:"

ThtSé Jiva

B9UaIAY 34€07N0NE
39¥aaAU 3a0730IS
39¥43A 3137dH09

$aau93a *SA aa

“NagLibd

UNN3INS ababe

O2 N3LLb

2'et- =

ge°e =

6622 =

@ 341

(Wad) 43NOd AYA
(93s) d01a3d
(2HM) AON3NO Bas

A-44


Hutsp soytweTy soy 3e paeanseaW urez3eg euUezUY S-YSY OTIeIUO

Ald? 80° O24

StTyeubeW Se 3e peyuTod Ysta ueA SHSU

Atay eorozs $334893d 90° o2-

——

pi
prezZzt 3WIL szsese 3iua
S33993d *SA dd ‘NYFLINd BNNSINY abaBa
€°9€- = B9vaahy 3d07NINE V'ss- = (Wad) aaM0d AYad
g'rt~ = 39va3AH 34073CTS bie = (939S)d01aad
g'ee- = 39WNRAW 31371dN09 e@1se = (ZHW)AON3NOaNSs

*"G@-w eanbtg

eo°as-

Wega
HIoW
OL 734
yanod
aqaoa

Alas
e00"S+

eoe*s+

A-32


the interfering signal pulse amplitude distribution would be
very difficult to predict. Also, the effect of multipathing
due to buildings and other structures would be difficult to
predict and very subjective. One approach to modeling these
propagation phenomena would be to develop an empirical mutual
environmental antenna gain model which would incorporate the
statistical pulse amplitude distribution of these propagation
related phenomena. This could be done by classifying the
environment into several categories, such as:

1. Free-space coupling environment.

2. Free-space with foreground clutter.
3. Moderate multipath coupling.

4. Heavy multipath coupling.

The major drawback to the empirical approach is that numerous
additional measurements would be required to determine what

the mutual environmental antenna gain model distribution should
be for each category. Even if empirical models were developed,
the actual implementation of the models would still be subjec-
tive. Since multipathing of interfering signals through mountain
ranges only occurred on a few paths, it appears that a measure-
ment program would not be practical. However, it is apparent
that without incorporating these propagation related phenomena
into the radar-to-radar interference prediction model, realistic
prediction of the interference on the PPI display cannot be

achieved.

A-49


oTIeUBeN oBLZ Fe Hutzutod ystd ueA swWwSY
Hutsn soztwety Soy }e peanseew utezjed eUuUazUY G-uSY YOReG HuoT ‘pz-w sanbtg

O° aser Ald’ 90°62+ oO ost+ Atay ooroz+ $394934 ee°az-

eo*os-

+ CEES
NIUW
jq--4 OL 738
yInod
aaa

pecs atas
eee"S+

c+
9Or1é1 GWIL Szsose 31¥d peers

: S33Y99d “SA Wad ‘“NABLLUd UNNGLNY Bodo

‘ 8'6e- = F9vyIAY 3407NIvE 2°ut- = (Hdd) aaMOd Awad
2°2e- = 39beaAy adO1adIS 29° = (99S)d0183d
€°Se- = 39vNFAY FL91GNOD 2222 = (ZHW)AINANOBaS

A-31


G-aSv OTTeZUO FO UASZVed UOTFETPRY eUuUszUY paansed; *g-v eandt4

o*ose+ Ald? 00° 02+ oroat+ Ald? ooroze 394934 09° 9z-
7 H eo'sz-
1 ‘
! ‘
pe eees Bee
‘ '
ote el ee
1 '
‘
Hi
----}-4 Bae
‘
'
= waa NI
43mod
Bad
aaoa
Ata
ooe'se
eo"se+
S2'st- = NYIGIW 3407NIbE S33¥93d "SA WAG ‘SNADLAbd YNNGLNY YvaUd
ee's- = NUtdaW 34073CTS 96ST" Ez (Mad) YINOd AYAd
62°€1- = NYIG3W 3137dN09 8o'h = (99S) a01aad

ea°Zt- = 39beIAN 31397GN09 s*tze2 = (2HW)AIN3NOaa4


STePeY ZHD 6°7-L°Z
JO UoTANGTAASTd UTeD euUszUY eATJeET[NUND peberoaAy ‘*O7-v saANbtTy

GaqgagoxXa AWIL dO &

66 86 S6 06 OL oS Of oT S ¢ oT

NIWD
A-22

(fap)

0@

Ov

09


Figure A-31 shows the Los Alamitos antenna pattern
measured using the Long Beach ASR-5 antenna operating in the
vertical polarization mode. A comparison of Figure A-30 and
A-31 shows that the mainbeam level has been attenuated by
6.2 dB (44 dBm - 37.8 dBm). The reason for this attenuation
is due to the radar antenna polarization (Long Beach operating
vertical and Los Alamitos operating horizontal). Also, a
comparison of Figures A-25 and A-26, for the two different
polarizations, shows that the average backlobe level is
-71 dBm. This is expected since the polarization of the
backlobes of a radar antenna are random.

Burbank ASR-6 - Figure A-32 shows the Burbank ASR-6
environmental antenna pattern measured at Long Beach with
the RSMS van dish pointed at 319.6° magnetic. The pulse
train separator, AS-330, was used to discriminate against
the Long Beach signal. A comparison of Figure A-32 with
Figure A-4 shows that there is a significant amount of multi-
pathing caused by the Santa Monica mountain range, with
Griffith Peak (altitude 1821 feet), which is between the two
radars. The multipathing occurring between 270° and 300°
is due to reflection off the San Gabriel mountain range with
altitudes of up to 4000 feet.

Mountain View

Measurements of environmental antenna patterns of other
radars were also made at the Mountain View ASR-5 radar site
using both the RSMS van dish antenna and the antenna of the
ASR-5 radar. The RSMS van dish antenna height is 14 feet,
and the ASR-5 antenna height is 26 feet. The following is
a discussion of the environmental antenna patterns measured
at the Mountain View radar site.

Oakland ASR-7 - Figure A-33 shows the Oakland ASR-7
antenna pattern measured at the Mountain View radar site
using the RSMS van dish pointed at 312° magnetic. A line-of-
sight antenna pattern of the Oakland radar was not measured.
Taking into consideration the tilt angle (3°) of the Oakland
ASR-7 antenna, the mainbeam gain at zero degrees elevation
is approximately 29 dBi (34 dBi -5 dB) using Figure A-2.
Therefore, the mean backlobe level is -9.6 dBi which is close
to the average median backlobe level (-12.85 dBi) given in
Table A-1 for line-of-sight antenna radiation patterns. Thus
the environmental antenna pattern of the Oakland ASR-7 radar
measured at Mountain View was not significantly altered by
propagation related phenomena, and, therefore, has statistical
characteristics similar to typical line-of-sight antenna

A-39


butsn yoeeg Hhuoy ye peinseepW ur9ez}eq PUuUezUY P-NdD/NY SOR TWeTY SOT

oTzoubew

ob 'L6 FL pazuTod pue uoTReZTAeTOg TeOTZIaA UT euUezUY JePeY S-usY

Ald’ oo°Gz+

Ala’ Gores

$334930
oo°or-

7

' '
‘ ‘
‘ ‘
v 7
‘ ‘
‘ ‘
' ‘

geter

QWI4 6290G2 31ba

AIVSIAY JdOTNIYE
39va3Au Ja0T13GIS
390834 3191409

$333930

"SA wad

“Nagiitd

UNNILING avdbs

br- = (Wad) SINOd HYBd
b2°e = (99S) dO1e3ad
tosz = (ZHW)ASN3NO3a4

“Te-v eanbta

90° as-

Wu3d
NIBH
O1 434
yanod
aaa

Alas
eoa'S+

A-40



6°66

“siepey 9-uSv

yueqing pue G-uSsv OTIezUO JO UOTANGTAASTd UTeD euUsZUY TeNZnW

66 86

S6

06

GaqdgaoXxa AWIL dO &

OL OS oe

oT S 4

“€@-W oanbta

To"

09-
Ov- 3
J
b
3
i Aaaht od
2
a
= oo
es
0 § «a
0%
OF

09


the horizon). Figure A-2 shows a measured antenna elevation
pattern for the FAA ASR antenna that was used to adjust the
nominal mainbeam gain. The antenna specifications for the
ASR-4 through ASR-7 radars are the same with the ASR-4, ASR-5
and ASR-7 antennas being manufactured by the same company.
The ASR antenna elevation pattern was also used to adjust the
mainbeam gain for the GCA radars.

Figures A-3 through A-10 show the measured data of several
airport surveillance radar antenna radiation patterns. The
figures show the antenna radiation pattern from -20° to
+380°, where the angles are relative to the mainbeam occurrence.
The plot covers -20° before the occurrence of the first mainbeam
and continues 20° past the occurrence of the second mainbeam
giving a coverage of 400° (40° overlap) to permit full main-
beam observation. The radar frequency, antenna scan period,
peak received power in dBm, and antenna statistical information
are shown at the top of the figure.

Table A-1 summarizes the antenna measurements shown in
Figures A-3 through A-10 for three-level statistical repre-
sentation of the antenna radiation pattern characteristics
relative to isotropic. The following statistical data for
each measured antenna radiation pattern is contained in the
table:

1. The median anténna pattern level between 0° and 360°.

2. Peak sidelobe antenna pattern level between 3° and
25° on either side of the mainbeam.

3. Median sidelobe antenna pattern level between 3° and
25° on either side of the mainbeam.

4. Peak backlobe antenna pattern level between 25° and

SS5%'s

5. Median backlobe antenna pattern level between 25°
and 335°.

Also shown in Table A-1 are the mean and standard devia-
tion taken across the eight measured samples for the above
five categories. The mean of the median antenna pattern
levels shown in. the Table A-1 was found to be -11.8 dBi with
a standard deviation of 2.8 dB. Reference 18 states that the
mean of sampled median antenna pattern levels for an uncluttered
site was -12.1 dBi with standard deviation of 6.2 dB. The
mean of the median sidelobe levels shown in Table A-1l was
found to be -7.1 dBi with a standard deviation of 3.3 dB.


‘OTFOUBEW G6ZT FB pezUTOd YSTa ueA
SWSY bUTSN SVN PpeweTyY Fe pernseeW UXez}eq BUUSZUY G-YSY META UTeJUNOW ‘*y¢-v aINbTy

f" os-

ose ger Q

wuad
NIB
.. fot 13a
wanod
Gao

aq oe

@Sseot BWI 2trisz 310d @ N31ib @ 3dbL

S33493d “SA dd ‘NS3Libd YNNGLNY YbaUa
€°Ob- = 39VYIAY 3d0TNIVE T'S2- = (Wad) aaM0d ABad
9°Se- = J9vyaAU 3g0730IS e9'® = (93S) doraad

2°6€- = 39¥YRAN JL391dWOo SG2z = (2HW)AIN3NOBaS

A-47


“OTQOUBEW O60E FE PezUTOG eUUSZUY IepeYy META UTeQUNOW
SUTSO ABTA UTeZUNOW Fe PeINseoW UIEZQeq eUUeUY TT-NdW/NY epoweTY ‘se-v eandtTa

ose est °
aa es-
Phy ‘ wuad
NIBH
F ol 13a
wanod
me i aoa
aq e
Of6tel BWIL Etbise 3iva 62 N3L18 @ 34ul
S33¥93d “SA dO ‘NY3LLUd UNNGINY abaoY
Stee- = 39b43AN 3g07NINE 6*hI- = (Haq) aaMOd Abad
S*6Z- = 39va3AH aa0730IS vete = (93S)C0183d

S°ze- = F9KaaIAN FLaIdWOD S°@622 = (ZHW)AON3NOBYS

r

A-45


The mean of the median backlobe levels for the sample shown

in Table A-1 was found to be -12.8 dBi with a standard devi-
ation of 3.1 dB. Reference 13 states that the median back-
lobe level for an average-siting condition should be -10.0 dBi.
with a standard deviation of 6.0 dB. Therefore, the measured
antenna radiation pattern statistics for airport surveillance
radars taken during the Los Angeles and San Francisco investi-
gations is in close agreement with previous measured data.

Line-of-sight antenna radiation pattern measurements were
also made on the Sacramento WSR-57 radar which has a parabolic
dish type antenna. The weather radar has the capability to
tilt in elevation the parabolic dish at angles between -5°
to +45° with the horizon. The WSR-57 at Sacramento is normally
operated with the antenna tilted in the elevation plan +1°
with respect to the horizon. The WSR-57 radar antenna has
a nominal mainbeam gain of +36 dBi, and a 3 GB beamwidth of
two degrees. Figures A-1l1 through A-13 show measured antenna
radiation patterns for tilt angles of zero, one, and two
degrees, respectively. The statistics in Figure A-1l show
an average backlobe level of approximately -7.2 dBi for the
parabolic dish. A comparison of Figures A-11l through A-13
illustrates the reduction in mainbeam gain due to the narrow
beamwidth of the pencil beam antenna for only a small change
in the elevation tilt angle of the antenna. This indicates
that the normal operating antenna tilt angle of weather
radars must be considered in predicting interference to and
from weather radars.

CUMULATIVE DISTRIBUTION MODEL

Figures A-14 through A-19 show the cumulative antenna
radiation pattern distribution of several radars listed in
Table A-l. The dotted line on the graph shows the 0 to 10
percent probability of exceeding a specified antenna gain
level. The solid line shows the 0 to 100 percent probability
of exceeding a specified gain level. Figure A-20 shows the
mean and 20 cumulative distribution taken from Figures A-14
through A-16, A-18, and A-19. Figure A-17 was not included
in the averaged statistics because of the unusally high
backlobe level due to hangar reflections. An examination of
Figure A-20 shows the standard deviation is decreasing as the
percentage of time exceeded is increasing from 80% to 100%.
In theory, this should not be true due to variations in site
clutter. This indicates that the measurements have been
biased due to insufficient dynamic range of the measurement
receiver. This is discussed in Appendix G.

A-15


ase

LS-USM OZUSWeTDeS JO uta}ZeT UO TeTpey euusjZuy pomnsesy

ol FO 3TTL euusjzuYy TOF

*ZI-W ernbtg

aad @s-

CLELS
NIBH
joL 13a
aanod
aqaga

seecst

z*6e-
vee
s*2e-

BWIL = =6o9TTTS2 31ea

39MaaAN 3EO1NIVE
39baIAY JaO1FdIS
39¥aaAW 3L37dN09

$334930a

“SA

: 69 N3Lib @ 3dbL
“NU3LL0d UNNZLINY YoaEs

6°Se = (HEC) 43ROd AY

s9'6t = (93S)d01a3d

2882 = (ZHW)AININO3ZaS

A-17


Mainbeam Region: Gain: Nominal mainbeam gain minus
correction for antenna tilt angle

Degrees: 357° to 3°
Sidelobe Region: Gain: -4 dBi

Degrees: 3° to 25° and 335° to 357°
Backlobe Region: Gain: -10 dBi

Degrees: 25° to 335°

Airport surveillance radars with cosecant squared elevation
antenna patterns normally tilt the mainbeam of the radar above
the horizon to reduce ground clutter; therefore, the energy
radiated at an elevation angle of zero degrees may be typically
5 to 12 dB below the actual mainbeam gain. Based on a sta-
tiscal analysis of the line-of-sight antenna radiation patterns
measured in the Los Angeles investigation, an antenna gain
level of -13 dBi in the backlobe region was used in the San
Francisco investigation.

LINE-OF-SIGHT ANTENNA PATTERN MEASUREMENTS

During the Los Angeles and San Francisco investigations,
several line-of-sight antenna radiation patterns were measured.
These measurements were made at the radar site and include
the environmental and clutter effects of the area which cause
extraneous reflections of the transmitted signal. When
possible, care was taken to minimize surface and obstacle
reflections. Methods outlined in Reference 17 were used to
determine the optimum measurement distance to minimize the
environmental clutter effect. All the measurements were made
at distances slightly greater than the far field distance
of D2/r, where D is the size of the aperture and A is the
wavelength.

All the measurements were made with reference to absolute
power received or relative to the mainbeam gain. However,
for EMC application, the antenna radiation characteristics
need to be referenced relative to an isotropic radiator. In
order to convert the measured antenna pattern data relative
to an isotropic radiator, the antenna elevation radiation
pattern characteristics were required in order to adjust the
antenna nominal mainbeam gain by the electrical and mechanical
tilt angle of the antenna and the measurement angle (angle of
the measurement van antenna and radar feed horn relative to


ot zouben

of 'L6 3 PezUTO pue UOTZeZTAIeTOd AeTNSITD ut euuszUY AepeY G-usv
butsn yoeeg buoy ye pernseeW ure3}eq BUUezUY P-NdO/NW SOJTWETY SOT ‘Og-y eanbTy

233493a

eres y 41d OG*Oz+ 90° 02-

o0°oS~

aa: ---- waa
NIbM
---NM} 01 43a
a3nog
aagy

= alge
e00°S+

€°9 3WIL 62S0S2 3Lud eo0'S+

$33493d “SA Wad ‘NddLibd UNNGINY YbaHa
€f- = 39beRAN Sd07NINE 8° 2e- = (Mad) a3NOd AYId
2°u2- = 39bagAH BG077dTS 22° = (939S)00183d
1e= = 39ba3AH 3131dN09 Tesz = (ZHW)AONaNOBas

A-38


TABLE A-2

ANTENNA RADIATION PATTERN STATISTICS
OF ONTARIO ASR-5 RADAR

GAIN IN CUMULATIVE [CUMULATIVE PROBABILITY
aBi (Gl;) BIN COUNT|SUM - PROBABILITY |DISTRIBUTION
(a; )

27 at 1 28 28
25 as 2 56 28
24 at 3 83 28
23 a 4 1.11 28
aly 1 | 1,39 28

9 at 6 1,67 28

. 2 8 2a: 255

2 a 9 2.50 28

a 2 EL 3.06 56

0 4 A5: ao, eid
=) 3 18 5.00 83
~2 4 22 6.21. pips
-3 16 38 10.56 4.45
-4 als 5: Bly ee i. 0L
-5 8 59 16.39 Zee
ea) 9 68 18.89 2.50
-7 17 85 23.61 4et2
-8 11 96 26.67 3.06
=o 27 23 34.17 7.50
-10 Lt 134 S122: 3205
etal 35 169 46.94 9.72
“12 19 188 §2.22 5.28
“13 Su: 239 66.39 14.17
-14 29 268 74.44 8.05
=15 32 300 83.33 8.89
-16 16 316 87.78 4.45
-17 25 341 94.72 6.94
-18 } 350 Di ee 2.50
Ets.) 6 356 98.89 1.67
=20 1 357 S95 1:7. -28
21 2 359 99.7 «55
-23 ah 360 100.00 28

A-26


PCTATICH

-———OAT REAM REGINN

SIDELOBE

RESICH

SIDELOBE
REGION

BACKLOBE PESION

Figure A-1. Three Level Antenna Pattern Representation




Hhutsn sop TWweTYV

soT 7 pernseeW ur9e33edq euUsjUY S-YuSY OTIeQUO

OTPOUHeW COP 3e PezUTOG eUUSzUY- P-NdO/NV

$33493a
a oece Ald’ 90°0z+ e'est+ Alds 00° 82+ 90° oz-
7 ’ 7 i ‘ : :
‘ ‘ ‘ ' 4 ‘
‘ + ‘ 4 ‘
' 1 + rf ‘ ‘
1 ‘ f ‘
aoe ---- + == eee ery
1 ' 1
'
+
S6'28- = NYIG3N JdOTNIbE S39999d “SA Hdd *NASLLNd YNNSINY abaUe
tr'sé- = NUIG3W 340730TS gser°z9- = (Had) NIMOd AY3d
¥8°29- = NVIG3IW J3L137dHO9 99° h = (99S)d01a3d
69°2@8- = 39¥N3AN 3137GH09 192 = (ZHN)ADNINDIaS

"L@-w eanbta

90°06-

waa NT
sanod
wad
aaoa

Alas
e0e*s+

A-34


radiation patterns.

Alameda NAS AN/MPN-1l1 - Figures A-34 and A-35 show the
Alameda AN/MPN-11 antenna pattern measured at the Mountain
View radar site using the RSMS van dish and ASR-5 radar
antenna, respectively. The antennas were pointed at 309°
Magnetic. A line-of-sight antenna pattern of the Alameda
AN/MPN-11 radar was not measured. The tilt angle on the
Alameda AN/MPN-11 radar antenna is 3.5 degrees. Therefore,
the mainbeam gain at zero degrees elevation is approximately
26 dBi using Figure A-2. With a mainbeam gain of approxi-
mately 26 dBi, the statistics shown in Figures A-34 and A-35
indicate an average backlobe level of -5.9 dBi and -7.5 dBi,
respectively. The high backlobe level of the Alameda AN/MPN-11
environmental antenna pattern measured at Mountain View may be
due to the high clutter in the vicinity of the Alameda NAS.
The NAS had numerous hangars in the area, and the San Francisco
skyscrapers and the San Francisco and Oakland bay bridge were
within line-of-sight. It is believed that the two high spikes
in Figure A-34 and the one spike in Figure A-35 around 180° are
due to reflections off the San Francisco-Oakland bay bridge.

Alameda NAS

Measurements of environmental antenna patterns of other
radars were also made at the Alameda NAS AN/MPN-11 radar site
using the RSMS van dish antenna. The RSMS van dish antenna
height (14.0 feet) was approximately the same height as the
antenna on the AN/MPN-11 radar.

Oakland ASR-7 - Figure A-36 shows the Oakland ASR-7
antenna pattern measured at the Alameda NAS radar site using
the RSMS van dish antenna pointed at 120° magnetic. For
a mainbeam gain of approximately 29 dBi at zero degrees
elevation, the statistics in Figure A-36 show a median
backlobe level of approximately -10.3 dBi (+29 dBi - 39.3 dB)
which is relatively close to the -12.85 dBi average median
backlobe level given in Table A-1l.

Mountain View ASR-5 - Figure A-37 shows the Mountain
View ASR-5 antenna pattern measured at the Alameda NAS radar
site using the RSMS van dish antenna pointed at 129° magnetic.
A line-of-sight antenna pattern of the Mountain View ASR-5
antenna pattern was not measured. The tilt angle on the
Mountain View ASR-5 radar antenna is three degrees. There-
fore, the mainbeam gain at zero degrees elevation is approxi-
mately 29 dBi using Figure A-2. With a mainbeam gain of
approximately 29 dBi, the statistics shown in Figure A-37

A-43


as a function of the azimuth orientation of the victim and
interfering antennas. Other parameters which contribute to
the power level received as a function of the azimuth
orientation of the victim and interfering radar are discussed
in the next section.

ENVIRONMENTAL ANTENNA PATTERN MEASUREMENTS

In addition to line-of-sight antenna patterns at the
victim and interferer radar sites, environmental modified
antenna patterns of interfering radars were measured at the
victim radar site during the Los Angeles and San Francisco
area investigations. The main objective of these measure-
ments was to determine if the environment was altering the
received interfering power level as a function of azimuth
orientation of the victim and interfering antennas in addition
to the variation due to free-space antenna coupling. Measure-
ments made during the Los Angeles-San Francisco area investi-
gations revealed several cases where multipath wave inter-
ference, arising from multiple scattering of the waves by
mountains, buildings and other structures, was occurring
which significantly changed the statistical distribution of
the interfering power level at the victim receiver RF input
resulting in unpredicted interference.

From an electromagnetic theory viewpoint, the multipathing
(terrain and building reflections) of the interfering signal
is a propagation phenomena. However, the effect of these
propagation phenomena is to alter the received interfering
power level as a function of the azimuth orientation of
the victim and interfering antennas. Actually, the multi-
pathing of interfering signals and the antenna pattern
characteristics of the victim and interferer antennas are
statistical parameters which are very difficult to separate
in the real environment. Therefore, from a modeling aspect
of the multipathing phenomena, it appears that it would be
more practical to incorporate the modeling of multipathing
with the mutual antenna gain distribution model.

The following is a discussion of the environmental
modified antenna patterns of potential interfering radars
made at the victim radar sites. Because of differences in
antenna heights and antenna patterns of the victim radar
antenna and RSMS van dish antenna, extreme care was required
in extrapolating data measured with the RSMS van dish antenna
to what the victim radar antenna would see. Also, in some
cases, due to low received interfering power level, a complete
interfering antenna pattern could not be measured. These

B-29


SS-Ndd/NV day STAPIL Jo uz9}3eg UOTIeTpPeY euuszUy peANseeW “OT-W eInhtTd

ost
ad os-

ove

ae nua

NIBW

o1 73a

wanod

aaaa

“ aq e
eeeert AWIL 9tTIs2 3iba eo N311u @ 3dbL

S33Y93d "SA @@ ‘NY3L1bd BNNZINY Ybaua

2°9€- = 39NYRAN JMO 1NIVE 9° re = CHEGIEINOd AKI
e°ee- 39NaaAN Ja073GIS 69°p = (93S) 001830
Tesz2 = (ZHW)AININOIYS

€*Se- = 39¥NRAK 3137409

A-13


ase

LS-USM OJFUSWeTDeS FO urEqzVed

00 FO ITT, PuUaqUY TOF

ost +

uoTJeTpey euuezuy pernseowW

“TI-w eanbta

id OS=

Wu34
NIBW
Jo. 138
eanod
aaos

Beecst

2 eb-
6°se-
O° The

WIL 8 «69tTIsé aiva

B9UYIAB 3G07NINE
39baa3AH 340730TS
39NY3AH 3137dH09

s334a93a

“SA aa

“NUZLi0d BNNSINY Sudes

62 N31lb 6 3dtL

8°6e =
2°6
2882 =

(WE0)839NOd ABId
T= (938)d0183d
(ZHH)DAININOZES

A-16