AESA Radar range calculator

Cockpit, radar, helmet-mounted display, and other avionics
  • Author
  • Message
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1444
  • Joined: 27 Mar 2015, 16:05

Unread post05 Sep 2017, 03:39

This is a table made by Stealthflanker (very knowledgeable guy) to predict radar ranges based on inputted variables such as pulse integration, scan sectors, antenna weighting scheme...etc.
http://www.mediafire.com/file/7wrkyslc1 ... Trial.xlsx
https://forum.keypublishing.com/showthr ... calculator

If that version is too complex for you, you can try this simplified table where many of the variables are pre calculated and more user friendly.
http://www.mediafire.com/file/7wrkyslc1 ... Trial.xlsx
For filling guide for PRF and pulse width you can check the following table:
radar_a2a_by_stealthflanker-dbf5rk5.png

radar_atg_modes_by_stealthflanker-dbf5rk2.png


i took the initiative and try estimate APG-81 range with some assumed variables: :mrgreen:
T/R modules: 1626
Peak power per module: 10W
Operational wavelength: 2.5 cm
Aperture weighting: Cos^4
Radar PRF: 10 Khz, Pulse width: 20 micro sec => Duty cycle: 20 %
Scan time frame: 9 seconds for full field of regard.
Scan field of regard: 120° azimuth, 10° elevation (with the same scan time frame, wider field of regard will result in shorter dwell time => shorter range)


=> Against target with RCS = 1m2
Maximum detection range with 50% probably of detection = 260 km
Maximum detection range with 90% probably of detection = 162 km

APG-81.PNG

APG-81 2.PNG
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1444
  • Joined: 27 Mar 2015, 16:05

Unread post05 Sep 2017, 04:55

Slightly different assumptions for APG-81:
T/R modules: 1626
Peak power per module: 10W
Operational wavelength: 3 cm
Aperture weighting: Taylor40D
Radar PRF: 10 Khz, Pulse width: 20 micro sec => Duty cycle: 20 %
Scan time frame: 9 seconds for full field of regard.
Scan field of regard: 20° azimuth, 10° elevation (Cued search => longer dwell time => longer range)
APG-81.PNG

=> Against target with RCS = 3m2
Maximum detection range with 50% probably of detection = 391 km
Maximum detection range with 90% probably of detection = 242 km
Offline

sprstdlyscottsmn

Elite 3K

Elite 3K

  • Posts: 3518
  • Joined: 10 Mar 2006, 01:24
  • Location: Phoenix, Az

Unread post05 Sep 2017, 05:31

I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.
"Spurts"

-Pilot
-Aerospace Engineer
-Army Medic
-FMS Systems Engineer
Offline

wrightwing

Elite 2K

Elite 2K

  • Posts: 2819
  • Joined: 23 Oct 2008, 15:22

Unread post05 Sep 2017, 06:42

Try the calculations using 16w modules.
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2458
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post05 Sep 2017, 09:23

sprstdlyscottsmn wrote:I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.


Yes, that's the result I got from calculating using similar formulas, variables and constants. Basically all PESA and MSA radars have to combat about 6 dB higher losses in transmit and receive paths together and thus smaller and less powerful AESA can have equal or superior range performance. This is in situation where there is no interference (like EW) or clutter. When those are present, AESA will be much better due to many factors.

Nice to see someone make such a easy to use Excel calculator for AESA radar range calculations. I'm definitely going to use this from now on! :D
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1444
  • Joined: 27 Mar 2015, 16:05

Unread post05 Sep 2017, 13:20

sprstdlyscottsmn wrote:I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.

The first one is volume search
The second is cued search, so the detection range get much longer just like hornetfinn said.
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1444
  • Joined: 27 Mar 2015, 16:05

Unread post05 Sep 2017, 13:21

wrightwing wrote:Try the calculations using 16w modules.

I don't know the exact peak power of APG-81 modules, so i play on the safe side and choose a small value.
Online
User avatar

playloud

Active Member

Active Member

  • Posts: 229
  • Joined: 13 Nov 2006, 04:07

Unread post05 Sep 2017, 15:46

I take it this assumes a clean sky (no competing RF creating interference or EW)?
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1444
  • Joined: 27 Mar 2015, 16:05

Unread post05 Sep 2017, 16:42

playloud wrote:I take it this assumes a clean sky (no competing RF creating interference or EW)?

Yes, no jamming or clutter.
Offline

sprstdlyscottsmn

Elite 3K

Elite 3K

  • Posts: 3518
  • Joined: 10 Mar 2006, 01:24
  • Location: Phoenix, Az

Unread post05 Sep 2017, 16:47

Is there one of these input variables that could be used to simulate that? What types of jamming even effect an AESA?
"Spurts"

-Pilot
-Aerospace Engineer
-Army Medic
-FMS Systems Engineer
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2458
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post06 Sep 2017, 10:48

sprstdlyscottsmn wrote:Is there one of these input variables that could be used to simulate that? What types of jamming even effect an AESA?


No, there isn't any input variable for that, although that might be simulated to some degree by adding jamming power to radar loss budget. That would simulate very wideband noise jamming effects. I don't think there is a way to simulate effects of other jammers with such a general calculator. We would need very detailed radar and jamming simulator to evaluate jamming effects.
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1444
  • Joined: 27 Mar 2015, 16:05

Unread post06 Sep 2017, 17:26

With the same duty cycle, detection range is longer by 12% if pulse width is the main contributor instead of PRF. Why?
PRF_is_bigger.png
Offline
User avatar

linkomart

Senior member

Senior member

  • Posts: 365
  • Joined: 31 May 2010, 07:30
  • Location: Sweden

Unread post07 Sep 2017, 08:28

hornetfinn wrote: I don't think there is a way to simulate effects of other jammers with such a general calculator. We would need very detailed radar and jamming simulator to evaluate jamming effects.


Yes... and no.
Just like any other calculator the basic formulaes are (rather) simple and can be put in excel. I have used a few of those and they work fine. The problem is to know the caractheristics of the jammer. Ant that is something you won't find on the net.

regards.
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2458
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post07 Sep 2017, 09:38

eloise wrote:With the same duty cycle, detection range is longer by 12% if pulse width is the main contributor instead of PRF. Why?


Because the amount of energy delivered to target and then back to radar is a product of transmitted power and duration of pulse. So radar gets more powerful return signals when pulse width is longer. Higher PRF improves detection range to some degree, but pulse width affects range more. Of course things are not this simple and longer range is not always really wanted since it can affect other performance factors too much. Best overall performance is usually achieved by balancing PRF and pulse width.
Offline

ricardonb

Newbie

Newbie

  • Posts: 6
  • Joined: 10 Feb 2017, 00:34

Unread post28 Oct 2017, 00:10

Is the difference between 50% and 90% PD not too large?
Next

Return to F-35 Avionics

Who is online

Users browsing this forum: No registered users and 3 guests