# JRG-41 

## United Kingdom

**ITU-R JRG 1A-1C-8B**

**Airborne radar systems.**

##### Stephen Parry -- NATS 

> **23^rd^ May 2005**

### 1 Background

The work program of the JRG calls for specific studies to determine the
characteristics of airborne radar systems. This document provides some
information on the use of airborne weather radar and the annex contains
characteristics of some 9 GHz airborne radar systems found in the UK.
The information was collated for an earlier study published by the UK
Radiocommunications Agency and which may be found at the following link
(to a 6.5 MB file).

<http://www.ofcom.org.uk/static/archive/ra/topics/research/topics/s-studies/civil-radio-systems.pdf>

##### 2 Meteorological Radars Airborne (X-Band)

These types of radars are used in commercial and general aviation to
detect weather phenomena such as storms and wind-sheer. Some systems are
also capable of interrogating Search And Rescue Transponders (SARTs) and
RAdar beaCONs (RACONs). General aviation pilots also use these systems
for ground mapping to aid navigation.

The majority of installed systems are Magnetron based however solid
state systems are now coming into service. Of the Magnetron systems
there are many system variants generally based on antenna size.

Airborne weather radar is intended to detect and display hazardous
weather systems that present a potential danger to the aircraft. The
types of weather systems that present the greatest potential danger are
wind shear and microbursts, which frequently exist in thunderstorms.

Wind shear is a term given to two wind currents blowing at different
speeds or directions close to each other. This can cause eddy currents
and areas of extreme turbulence in the space between the two wind
currents.

Microbursts are sudden violent downward air currents that occasionally
exist beneath thunderstorms. They tend to exist close to the ground,
where they pose maximum risk to aircraft on final approach. There have
been many fatal accidents attributed to microbursts, one of the best
documented being the Delta Airlines l-1011 that crashed at Dallas Fort
Worth Airport in February 1985.

Figure 1 shows a typical display of an airborne weather radar, the
weather targets are colour-coded by the intensity of the return. The
display correlation to approximate rainfall is given in Table 1 below.

Table 1 Colour/rainfall correlation

  ------------- ---------------------------- ----------------------------
  Colour        Echo strength                Rainfall rate

  Black         Very light or no returns     Less than 0.7 mm/hr.

  Green         Light returns                0.7 - 4 mm/hr

  Yellow        Medium returns               4 - 12 mm/hr.

  Red           Strong returns               Greater than 12 mm/hr.

  Magenta       Turbulence                   N/a
  ------------- ---------------------------- ----------------------------

Figure 1 Airborne weather radar display

![](media/image1.png){width="4.246527777777778in"
height="3.2777777777777777in"}

##### 3 Transmitter characteristics

Airborne weather radar transmitters operate at X-Band and may use either
magnetron or solid state technology. Without exception airborne weather
radar are forward looking systems. The antenna is usually of flat plate
construction that is housed behind a radome on the nose of the aircraft.
The antenna is fixed to a scanning mount that mechanically moves the
antenna from side to side continuously. The pilot also has the ability
to adjust the elevation axis of the antenna.

Figure 2 Airborne weather radar antenna and mount.

![](media/image2.png){width="2.3256944444444443in" height="2.9875in"}

##### 4 Interference considerations

An interfering RF source operating at a frequency close to the radar's
operating frequency can create unusual return displays on the cockpit
display (see Figure 3.1.1-8 below). These returns will appear as a
single wedge of radar return that extends from very close range (\< 5
nm) out to maximum range for the selected range scale. The wedge will
typically cover from 3 to 5 degrees in azimuth.

Figure 3 Airborne weather radar cockpit display in the presence of an
interferer

![](media/image3.png){width="4.284027777777778in"
height="3.115972222222222in"}

These patterns are caused by CW sources of interference. Types of CW RF
source that can cause this effect include:

military CW radar

radar jamming equipment

satellite uplink equipment

Adjusting the manual gain or the antenna tilt angle may help alleviate
the effect of the interfering source but the effect will not completely
disappear until the interfering source is no longer in the radar's field
of view.

Aircraft are more susceptible to bad weather during the approach phase
of flight. This is the time when weather radar is needed most. In this
phase of flight the aircraft has a nose-down pitch attitude and hence
the weather radar antenna points towards the ground. Some systems
automatically adjust the antenna pitch if ground clutter is detected.

The downward direction of the antenna makes the system most susceptible
to ground based interference in the most critical phase of flight (i.e.
during landing). Interference that degrades performance and hence masks
potentially dangerous weather cannot be accepted.

##### 

5 Generic system characteristics

A survey was made of the radar models installed in the UK; the
information from this survey was reduced to generic radar types based
upon the radar role and operational frequency band. The parameters for
these generic radar types/roles are discussed further in the source
document.

The annex lists the parameters of airborne weather radar models/types
identified as installed in the UK. The parameters listed have been
derived from a variety of sources, each source having its own level of
confidence. The main sources were:

-   Manufacturers published data;

-   Experience of similar Radar systems;

-   Assessment by experienced Radar Engineers.

Due to the varying levels of confidence that the data actually reflects
the installed systems, the annex only identifies the systems by their
role and a unique number.

Within the annex the following abbreviations are used:

N/A - (Not applicable) - means that the particular parameter is not
applicable to this type of radar.

NDA (No data available) - means that no data is available for this
particular parameter, although the parameter is thought to be
applicable.

The characteristics are reproduced here for the use of the JRG in its
work.

**Annex**

Key to tables

  ---------------------- ------------------------------------------------
  Platform type          Where the radar system is used; on land, at sea
  (airborne, shipborne,  or in the air
  ground)                

  Roles                  The purpose for which the radar is installed

  CHARACTERISTICS        

  Radar Band             The radar frequency band (L, S, C, Ku, or X) in
                         which this type of radar operates

  Tuning range (GHz)     The frequency range over which this radar can be
                         used

  Operational            The number of discrete frequencies that any one
  Frequencies            radar uses

  Specific operating     The actual operational frequency(ies) where it
  frequency              is not installation specific

  Modulation             The form of modulation applied to the radar
                         transmitter pulses using the ITU Radio
                         Regulation emission codes where applicable; most
                         radars use an unmodulated pulse

  Tx Power into Antenna  The peak power of the transmitter output pulse
  (kW)                   

  Pulse width (µs)       The width of the pulse amplitude measured
                         between the -3 dB points. Many radars use two or
                         more pulse lengths

  Pulse rise/Fall time   The rise and fall times of the transmitter
  (µs)                   output pulse measured between the 10% and 90%
                         levels

  Pulse repetition rate  The pulse repetition rate of the radar. Some
  (Hz)                   radars use a mixture of PRRs and others the PRR
                         changes with the selected display range

  Duty cycle (%)         The percentage of time that the transmitter is
                         transmitting ( the mark/space ratio)

  Chirp bandwidth (MHz)  The bandwidth of the FM modulation of the pulses
                         used on some radar types

  Phase-coded sub-pulse  *no radars of this type in civil use in the UK*
  width                  

  Compression ratio      The ratio by which the receiver compresses the
                         received pulses

  RF emission bandwidth  The bandwidth of the transmitted pulses measured
  (-3 dB) (MHz)          between the -3 dB points

  RF emission bandwidth  The bandwidth of the transmitted pulses measured
  (-20 dB) (MHz)         between the -20 dB points

  RF emission bandwidth  The bandwidth of the transmitted pulses measured
  (-40 dB) (MHz)         between the -40 dB points

  Output device          The type of device used as the final output
                         power amplifier in the transmitter

  Antenna pattern type   The shape of the elevation beam produced by the
  (pencil, fan,          radar antenna
  cosecant-squared,      
  etc.)                  

  Antenna type           The type of antenna fitted to the radar
  (reflector, phased     
  array, slotted array,  
  etc.)                  

  Antenna horizontal     The azimuth beamwidth of the antenna measured
  beamwidth (degrees)    between the -3 dB points

  Antenna polarisation   Whether the antenna radiates horizontal,
                         vertical or circularly polarised RF

  Antenna mainbeam gain  The gain of the antenna compared to an isotropic
  (dBi)                  radiator measured on the peak of the beam

  Antenna vertical       The elevation beamwidth of the antenna measured
  beamwidth (degrees)    between the -3 dB points

  Antenna horizontal     The rate at which the antenna beam rotates in
  scan rate              the azimuth plane
  (degrees/sec)          

  Antenna horizontal     Whether the antenna rotates continuously or
  scan type (continuous, performs a scan pattern
  random, 360 degrees,   
  sector, etc.)          

  Antenna vertical scan  The rate at which the antenna beam scans in the
  rate (degrees/sec)     elevation plane

  Antenna vertical scan  Whether the antenna scans continuously or
  type                   performs a scan pattern in the elevation plane
                         (i.e. continuous, random, 360 degrees, sector,
                         etc.)

  Antenna sidelobe       The level of the sidelobes with respect to the
  levels (1st SLs and    beam peak. Where only 1 figure is given, this
  remote SLs) (dB)       can be taken to reflect both SLs.

  Antenna height above   The height in metres that the electrical centre
  ground or sea (m)      of the antenna is above ground (or sea) level

  Receiver IF bandwidth  The bandwidth of the radar receiver response
  (3 dB) (MHz)           measured at IF and between the -3 dB points

  Receiver noise figure  The noise figure of the radar receiver
  (dB)                   

  Minimum detectable     The minimum signal that the radar receiver can
  signal (dBm)           detect in the presence of background noise and
                         in a clutter free region

  Receiver front-end 1   The power density into the radar antenna that
  dB Gain Compression    causes the radar receiver to have a 1 dB gain
  point. Power density   compression
  at antenna (W/m^2)^    

  Receiver on-tune       The power density into the radar antenna that
  saturation level Power causes the radar receiver to saturate
  density at antenna     
  (W/m^2)^               

  RF receiver 3 dB       The bandwidth of the radar front end receiver
  bandwidth (MHz)        measured between the -3dB points

  Proportion of time in  The Proportion of time that the radar is
  use                    normally in use
  ---------------------- ------------------------------------------------

  --------------------- ---------------- ------------------ ------------------
                        **Airborne-1**   **Airborne-2**     **Airborne-3**

  Platform type         Airborne         Airborne           Airborne
  (airborne, shipborne,                                     
  ground)                                                   

  Roles                 Weather          Weather            Weather

  CHARACTERISTICS                                           

  Radar Band            X                X                  X

  Tuning range (GHz)    9.3 to 9.5       9.3 to 9.5         9.3 to 9.5

  Operational           1                1                  1
  Frequencies                                               

  Specific operating    9.33 GHz         9.33 GHz           9.33 GHz
  frequency                                                 

  Modulation            P0N              P0N                P0N

  Tx Power into Antenna 0.145            0.035              0.035
  (kW)                                                      

  Pulse width (µs)      1 to 20          1.8,2.4,4.8,9.6,   1.8,2.4,4.8,9.6,
                                         19.2,28.8          19.2,28.8

  Pulse rise/Fall time  0.02             0.02               0.02
  (µs)                                                      

  Pulse repetition rate 180 to 9000      NDA                NDA
  (Hz)                                                      

  Duty cycle (%)        NDA              NDA                NDA

  Chirp bandwidth (MHz) N/A              N/A                N/A

  Phase-coded sub-pulse N/A              N/A                N/A
  width                                                     

  Compression ratio     N/A              N/A                N/A

  RF emission bandwidth 0.05 to 1 [^1]   0.035 to 0.55      0.035 to 0.55
  (-3 dB) (MHz)                          Error: Reference   Error: Reference
                                         source not found   source not found

  RF emission bandwidth 0.32 to 6.4      0.30 to 6.4 Error: 0.30 to 6.4 Error:
  (-20 dB) (MHz)        Error: Reference Reference source   Reference source
                        source not found not found          not found

  RF emission bandwidth 3.2 to 53 Error: 3.2 to 54 Error:   3.2 to 54 Error:
  (-40 dB) (MHz)        Reference source Reference source   Reference source
                        not found        not found          not found

  Output device         Solid state      Solid state        Solid state

  Antenna pattern type  Pencil           Pencil             Pencil
  (pencil, fan,                                             
  cosecant-squared,                                         
  etc.)                                                     

  Antenna type          Flat Plate       Flat Plate         Flat Plate
  (reflector, phased                                        
  array, slotted array,                                     
  etc.)                                                     

  Antenna horizontal    3.5              8                  8
  beamwidth (degrees)                                       

  Antenna polarisation  Pencil           Pencil             Pencil

  Antenna mainbeam gain 34.4             26                 26
  (dBi)                                                     

  Antenna vertical      3.5              8                  8
  beamwidth (degrees)                                       

  Antenna horizontal    NDA              27                 27
  scan rate                                                 
  (degrees/sec)                                             

  Antenna horizontal    60 degree Sector 120 degree Sector  120 or 60 degree
  scan type                                                 Sector
  (continuous, random,                                      
  360 degrees, sector,                                      
  etc.)                                                     

  Antenna vertical scan N/A              N/A                N/A
  rate (degrees/sec)                                        

  Antenna vertical scan tilt range ± 15  tilt range ± 15    tilt range ± 15
  type                  degrees          degrees            degrees

  Antenna sidelobe      -31 dB           NDA                NDA
  levels (1st SLs and                                       
  remote SLs) (dB)                                          

  Antenna height above  N/A [^2]         N/A Error:         N/A Error:
  ground or sea (m)                      Reference source   Reference source
                                         not found          not found

  Receiver IF bandwidth NDA              NDA                NDA
  (3 dB) (MHz)                                              

  Receiver noise figure 4dB              NDA                NDA
  (dB)                                                      

  Minimum detectable    -125             NDA                NDA
  signal (dBm)                                              

  Receiver front-end 1  NDA              NDA                NDA
  dB Gain Compression                                       
  point. Power density                                      
  at antenna W/m^2^                                         

  Receiver on-tune      NDA              NDA                NDA
  saturation level                                          
  Power density at                                          
  antenna W/m^2^                                            

  RF receiver 3 dB      NDA              NDA                NDA
  bandwidth (MHz)                                           

  Proportion of time in NDA              NDA                NDA
  use                                                       
  --------------------- ---------------- ------------------ ------------------

  --------------------- ------------------ ------------------ ----------------
                        **Airborne-4**     **Airborne-5**     **Airborne-6**

  Platform type         Airborne           Airborne           Airborne
  (airborne, shipborne,                                       
  ground)                                                     

  Roles                 Weather            Weather            Weather

  CHARACTERISTICS                                             

  Radar Band            X                  X                  X

  Tuning range (GHz)    9.3 to 9.5         9.3 to 9.5         9.3 to 9.5

  Operational           1                  1                  1
  Frequencies                                                 

  Specific operating    9.33 GHz                              
  frequency                                                   

  Modulation            P0N                P0N                P0N

  Tx Power into Antenna 0.035              0.035              0.15
  (kW)                                                        

  Pulse width (µs)      1.8,2.4,4.8,9.6,   1.8,2.4,4.8,9.6,   1 to 20
                        19.2,28.8          19.2,28.8          

  Pulse rise/Fall time  0.02               0.02               0.02
  (µs)                                                        

  Pulse repetition rate NDA                NDA                180 to 9000
  (Hz)                                                        

  Duty cycle (%)        NDA                NDA                0.36 to 0.9

  Chirp bandwidth (MHz) N/A                N/A                N/A

  Phase-coded sub-pulse N/A                N/A                N/A
  width                                                       

  Compression ratio     N/A                N/A                N/A

  RF emission bandwidth 0.035 to 0.55      0.035 to 0.56      1 to 0.05
  (-3 dB) (MHz)         Error: Reference                      
                        source not found                      

  RF emission bandwidth 0.30 to 6.4 Error: 0.22 to 3.56       0.3 to 64 Error:
  (-20 dB) (MHz)        Reference source   Error: Reference   Reference source
                        not found          source not found   not found

  RF emission bandwidth 3.2 to 54 Error:   2.2 to 35.6 Error: 3.2 to 54 Error:
  (-40 dB) (MHz)        Reference source   Reference source   Reference source
                        not found          not found          not found

  Output device         Solid state        Solid state        Solid State

  Antenna pattern type  Pencil             Pencil             Pencil
  (pencil, fan,                                               
  cosecant-squared,                                           
  etc.)                                                       

  Antenna type          Flat Plate         Flat Plate, 18     Flat Plate, 28
  (reflector, phased                       inch               
  array, slotted array,                                       
  etc.)                                                       

  Antenna horizontal    7                  6                  3.5
  beamwidth (degrees)                                         

  Antenna polarisation  Pencil             Pencil             Pencil

  Antenna mainbeam gain 27                 28                 35
  (dBi)                                                       

  Antenna vertical      7                  6                  2.5
  beamwidth (degrees)                                         

  Antenna horizontal    27                 27                 NDA
  scan rate                                                   
  (degrees/sec)                                               

  Antenna horizontal    120 or 60 degree   120 or 60 degree   NDA
  scan type             Sector             Sector             
  (continuous, random,                                        
  360 degrees, sector,                                        
  etc.)                                                       

  Antenna vertical scan N/A                N/A                N/A
  rate (degrees/sec)                                          

  Antenna vertical scan tilt range ± 15    tilt range ± 15    tilt range ± 15
  type                  degrees            degrees            degrees

  Antenna sidelobe      NDA                NDA                -30 dB
  levels (1st SLs and                                         
  remote SLs) (dB)                                            

  Antenna height above  N/A Error:         N/A Error:         N/A Error:
  ground or sea (m)     Reference source   Reference source   Reference source
                        not found          not found          not found

  Receiver IF bandwidth NDA                NDA                NDA
  (3 dB) (MHz)                                                

  Receiver noise figure NDA                NDA                NDA
  (dB)                                                        

  Minimum detectable    NDA                NDA                NDA
  signal (dBm)                                                

  Receiver front-end 1  NDA                NDA                NDA
  dB Gain Compression                                         
  point. Power density                                        
  at antenna W/m^2^                                           

  Receiver on-tune      NDA                NDA                NDA
  saturation level                                            
  Power density at                                            
  antenna W/m^2^                                              

  RF receiver 3 dB      NDA                NDA                NDA
  bandwidth (MHz)                                             

  Proportion of time in NDA                NDA                NDA
  use                                                         
  --------------------- ------------------ ------------------ ----------------

+---------------------+---------------+---------------+---------------+
|                     | *             | *             | *             |
|                     | *Airborne-7** | *Airborne-8** | *Airborne-9** |
+---------------------+---------------+---------------+---------------+
| Platform type       | Airborne      | Airborne      | Airborne      |
| (airborne,          |               |               |               |
| shipborne, ground)  |               |               |               |
+---------------------+---------------+---------------+---------------+
| Roles               | Weather       | Weather       | Weather       |
+---------------------+---------------+---------------+---------------+
| CHARACTERISTICS     |               |               |               |
+---------------------+---------------+---------------+---------------+
| Radar Band          | X             | X             | X             |
+---------------------+---------------+---------------+---------------+
| Tuning range (GHz)  | Fixed         | Fixed         | Fixed         |
+---------------------+---------------+---------------+---------------+
| Operational         | 1             | 1             | 1             |
| Frequencies         |               |               |               |
+---------------------+---------------+---------------+---------------+
| Specific operating  | 9.345 GHz     | 9.345 GHz     | 9.345 GHz     |
| frequency           |               |               |               |
+---------------------+---------------+---------------+---------------+
| Modulation          | P0N           | P0N           | P0N           |
+---------------------+---------------+---------------+---------------+
| Tx Power into       | 10 nom, 12    | 12 max.       | 3.5           |
| Antenna (kW)        | max.          |               |               |
+---------------------+---------------+---------------+---------------+
| Pulse width (µs)    | 1 or 2        | 1 or 2        | 1 or 2        |
+---------------------+---------------+---------------+---------------+
| Pulse rise/Fall     | 0.015         | 0.015         | 0.015         |
| time (µs)           |               |               |               |
+---------------------+---------------+---------------+---------------+
| Pulse repetition    | NDA           | NDA           | NDA           |
| rate (Hz)           |               |               |               |
+---------------------+---------------+---------------+---------------+
| Duty cycle (%)      | NDA           | NDA           | NDA           |
+---------------------+---------------+---------------+---------------+
| Chirp bandwidth     | N/A           | N/A           | N/A           |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Phase-coded         | N/A           | N/A           | N/A           |
| sub-pulse width     |               |               |               |
+---------------------+---------------+---------------+---------------+
| Compression ratio   | N/A           | N/A           | N/A           |
+---------------------+---------------+---------------+---------------+
| RF emission         | 1 to 0.5      | 1 to 0.5      | 1 to 0.5      |
| bandwidth (-3 dB)   |               |               |               |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| RF emission         | 2.2 to 8      | 2 to 4        | 2.2 to 8      |
| bandwidth (-20 dB)  |               |               |               |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| RF emission         | 50 to 150     | 50 to 150     | 50 to 150     |
| bandwidth (-40 dB)  |               |               |               |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Output device       | Magnetron     | Magnetron     | Magnetron     |
+---------------------+---------------+---------------+---------------+
| Antenna pattern     | Pencil        | Pencil        | Pencil        |
| type (pencil, fan,  |               |               |               |
| cosecant-squared,   |               |               |               |
| etc.)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna type        | Flat Plate    | Flat Plate    | Flat Plate    |
| (reflector, phased  | Slotted array | Slotted array | slotted array |
| array, slotted      |               |               |               |
| array, etc.)        | 12 inch dia.  | 12 or 18 inch | 10 or 12 inch |
|                     |               | dia.          | dia.          |
+---------------------+---------------+---------------+---------------+
| Antenna horizontal  | NDA           | NDA           | NDA           |
| beamwidth (degrees) |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna             | Horizontal    | Horizontal    | Horizontal    |
| polarisation        |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna mainbeam    | NDA           | NDA           | NDA           |
| gain (dBi)          |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna vertical    | NDA           | NDA           | NDA           |
| beamwidth (degrees) |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna horizontal  | NDA           | NDA           | NDA           |
| scan rate           |               |               |               |
| (degrees/sec)       |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna horizontal  | 120 or 60     | 120 or 60     | 120 or 60     |
| scan type           | degree Sector | degree Sector | degree Sector |
| (continuous,        |               |               |               |
| random, 360         |               |               |               |
| degrees, sector,    |               |               |               |
| etc.)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna vertical    | N/A           | NDA           | NDA           |
| scan rate           |               |               |               |
| (degrees/sec)       |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna vertical    | tilt range ±  | tilt range ±  | tilt range ±  |
| scan type           | 15 degrees    | 15 degrees    | 15 degrees    |
+---------------------+---------------+---------------+---------------+
| Antenna sidelobe    | -20, -25      | -20, -25      | -20, -25      |
| levels (1st SLs and |               |               |               |
| remote SLs) (dB)    |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna height      | N/A Error:    | N/A Error:    | N/A Error:    |
| above ground or sea | Reference     | Reference     | Reference     |
| (m)                 | source not    | source not    | source not    |
|                     | found         | found         | found         |
+---------------------+---------------+---------------+---------------+
| Receiver IF         | NDA           | NDA           | NDA           |
| bandwidth (3 dB)    |               |               |               |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Receiver noise      | NDA           | NDA           | NDA           |
| figure (dB)         |               |               |               |
+---------------------+---------------+---------------+---------------+
| Minimum detectable  | NDA           | NDA           | NDA           |
| signal (dBm)        |               |               |               |
+---------------------+---------------+---------------+---------------+
| Receiver front-end  | NDA           | NDA           | NDA           |
| 1 dB Gain           |               |               |               |
| Compression point.  |               |               |               |
| Power density at    |               |               |               |
| antenna W/m^2^      |               |               |               |
+---------------------+---------------+---------------+---------------+
| Receiver on-tune    | NDA           | NDA           | NDA           |
| saturation level    |               |               |               |
| Power density at    |               |               |               |
| antenna W/m^2^      |               |               |               |
+---------------------+---------------+---------------+---------------+
| RF receiver 3 dB    | NDA           | NDA           | NDA           |
| bandwidth (MHz)     |               |               |               |
+---------------------+---------------+---------------+---------------+
| Proportion of time  | NDA           | NDA           | NDA           |
| in use              |               |               |               |
+---------------------+---------------+---------------+---------------+

+---------------------+---------------+---------------+---------------+
|                     | **            | **            | **            |
|                     | Airborne-10** | Airborne-11** | Airborne-12** |
+---------------------+---------------+---------------+---------------+
| Platform type       | Airborne      | Airborne      | Airborne      |
| (airborne,          |               |               |               |
| shipborne, ground)  |               |               |               |
+---------------------+---------------+---------------+---------------+
| Roles               | Surface       | Weather &     | Weather &     |
|                     | mapping,      | turbulence    | turbulence    |
|                     | Weather &     |               |               |
|                     | Beacon        |               |               |
+---------------------+---------------+---------------+---------------+
| CHARACTERISTICS     |               |               |               |
+---------------------+---------------+---------------+---------------+
| Radar Band          | X             | X             | X             |
+---------------------+---------------+---------------+---------------+
| Tuning range (GHz)  | Fixed         | Fixed         | Fixed         |
+---------------------+---------------+---------------+---------------+
| Operational         | 1             | 1             | 1             |
| Frequencies         |               |               |               |
+---------------------+---------------+---------------+---------------+
| Specific operating  | 9.345 GHz     | 9.345 GHz     | 9.345         |
| frequency           |               |               |               |
+---------------------+---------------+---------------+---------------+
| Modulation          | P0N           | P0N           | NDA           |
+---------------------+---------------+---------------+---------------+
| Tx Power into       | 12 max.       | 12 max.       | 125 Watts     |
| Antenna (kW)        |               |               |               |
+---------------------+---------------+---------------+---------------+
| Pulse width (µs)    | 1 or 2        | 1 or 2        | 1.5, 6, 18    |
+---------------------+---------------+---------------+---------------+
| Pulse rise/Fall     | 0.015         | 0.015         | 0.02          |
| time (µs)           |               |               |               |
+---------------------+---------------+---------------+---------------+
| Pulse repetition    | NDA           | NDA           | 6000, 1600,   |
| rate (Hz)           |               |               | 380           |
+---------------------+---------------+---------------+---------------+
| Duty cycle (%)      | NDA           | NDA           | 1 max         |
+---------------------+---------------+---------------+---------------+
| Chirp bandwidth     | N/A           | N/A           | NDA           |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Phase-coded         | N/A           | N/A           | N/A           |
| sub-pulse width     |               |               |               |
+---------------------+---------------+---------------+---------------+
| Compression ratio   | N/A           | N/A           | N/A           |
+---------------------+---------------+---------------+---------------+
| RF emission         | 1 to 0.5      | 1, 0.5        | 0.8, 0.17,    |
| bandwidth (-3 dB)   |               |               | 0.06          |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| RF emission         | 2.2 to 8      | 2.2 to 8      | 5.1, 1.1, 0.4 |
| bandwidth (-20 dB)  |               |               | Error:        |
| (MHz)               |               |               | Reference     |
|                     |               |               | source not    |
|                     |               |               | found         |
+---------------------+---------------+---------------+---------------+
| RF emission         | 50 to 150     | 50 to 150     | 51.2, 10.7,   |
| bandwidth (-40 dB)  |               |               | 3.6 Error:    |
| (MHz)               |               |               | Reference     |
|                     |               |               | source not    |
|                     |               |               | found         |
+---------------------+---------------+---------------+---------------+
| Output device       | Magnetron     | Magnetron     | Solid State   |
+---------------------+---------------+---------------+---------------+
| Antenna pattern     | Pencil        | Pencil        | Pencil        |
| type (pencil, fan,  |               |               |               |
| cosecant-squared,   |               |               |               |
| etc.)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna type        | Flat Plate    | Flat Plate    | Flat Plate    |
| (reflector, phased  | Slotted array | Slotted array | Slotted array |
| array, slotted      |               |               |               |
| array, etc.)        | 5 sizes, 10   | 3 sizes 12,   | 2 sizes 30 &  |
|                     | to 24 inches  | 18 & 24       | 24 inches     |
|                     |               | inches        |               |
+---------------------+---------------+---------------+---------------+
| Antenna horizontal  | NDA           | NDA           | 2.9 & 3.6     |
| beamwidth (degrees) |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna             | Horizontal    | Horizontal    | Horizontal    |
| polarisation        |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna mainbeam    | NDA           | NDA           | 35, 33        |
| gain (dBi)          |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna vertical    | NDA           | NDA           | 2.9, 3.6      |
| beamwidth (degrees) |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna horizontal  | NDA           | NDA           | 45, 38        |
| scan rate           |               |               |               |
| (degrees/sec)       |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna horizontal  | NDA           | NDA           | Sector        |
| scan type           |               |               |               |
| (continuous,        |               |               |               |
| random, 360         |               |               |               |
| degrees, sector,    |               |               |               |
| etc.)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna vertical    | NDA           | NDA           | 38 or 45      |
| scan rate           |               |               |               |
| (degrees/sec)       |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna vertical    | tilt range ±  | tilt range ±  | tilt range ±  |
| scan type           | 15 degrees    | 15 degrees    | 15 degrees    |
+---------------------+---------------+---------------+---------------+
| Antenna sidelobe    | NDA           | NDA           | NDA           |
| levels (1st SLs and |               |               |               |
| remote SLs) (dB)    |               |               |               |
+---------------------+---------------+---------------+---------------+
| Antenna height      | N/A Error:    | N/A Error:    | N/A Error:    |
| above ground or sea | Reference     | Reference     | Reference     |
| (m)                 | source not    | source not    | source not    |
|                     | found         | found         | found         |
+---------------------+---------------+---------------+---------------+
| Receiver IF         | NDA           | NDA           | NDA           |
| bandwidth (3 dB)    |               |               |               |
| (MHz)               |               |               |               |
+---------------------+---------------+---------------+---------------+
| Receiver noise      | NDA           | NDA           | NDA           |
| figure (dB)         |               |               |               |
+---------------------+---------------+---------------+---------------+
| Minimum detectable  | NDA           | NDA           | NDA           |
| signal (dBm)        |               |               |               |
+---------------------+---------------+---------------+---------------+
| Receiver front-end  | NDA           | NDA           | NDA           |
| 1 dB Gain           |               |               |               |
| Compression point.  |               |               |               |
| Power density at    |               |               |               |
| antenna W/m^2^      |               |               |               |
+---------------------+---------------+---------------+---------------+
| Receiver on-tune    | NDA           | NDA           | NDA           |
| saturation level    |               |               |               |
| Power density at    |               |               |               |
| antenna W/m^2^      |               |               |               |
+---------------------+---------------+---------------+---------------+
| RF receiver 3 dB    | NDA           | NDA           | NDA           |
| bandwidth (MHz)     |               |               |               |
+---------------------+---------------+---------------+---------------+
| Proportion of time  | NDA           | NDA           | NDA           |
| in use              |               |               |               |
+---------------------+---------------+---------------+---------------+

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

[^1]: Estimated from pulse shape

[^2]: Many aircraft use their weather radar on landing