AESA Radar range calculator.

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8 years 6 months

Posts: 906

To do estimate one must use the good value for the radar. For the Standoff jamming case. We need to know the Sidelobe level of the Irbis and Zaslon. This information however is kinda hard to find but estimates are available. a Good generic rule of thumb to estimate sidelobe level of an array antenna is to divide 1 with number of elements, this rule of thumb however assume uniform illumination. The elements itself can be easily estimated with the AESA radar calculator's "TR Module number" spreadsheet. All need to be done is to input the antenna vertical and horizontal diameter to antenna area finder. and From there one can work out the estimate frequency band for the radar, which in here we take as 9300 MHz, as can be seen here :

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Then we can estimate the number of radiating elements of the Irbis and Zaslon with following result :

Irbis-E : 1960
Zaslon : 3267

From there we then can estimate average sidelobe level as follows :

Irbis : 10*LOG(1/1960) = -32.9 dB
Zaslon : 10*LOG(1/3267) = -35.14 dB

The emitted power would be :
Irbis-E : 20 Kilowatt or 20000 Watt or about 73 dBm
Zaslon : 10 Kilowatt or 10000 Watt or about 70 dBm

The antenna gain can be estimated from the number of elements or findings in open source.
Zaslon : 37 dB

For Irbis tho, some other estimate have to be made. We only know its diameter. then we need to calculate beamwidth. Easily be done through number of elements :
We assume uniform illumination, thus the beamwidth coefficient would be 0.886. The antenna beamwidth is then calculated to be :

BWirbis=0.886*(100/SQRT(1960))
BWirbis= 2 Degrees

Then using K barton's approximation, we can calculate the antenna gain as following 10*LOG(30000/(2*2)) = 38.7 dB.

Armed with those values. We can then estimate burn through range. With following result.

Irbis-E
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Zaslon :
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You can download the spreadsheet i made for above calculation here :

http://www.mediafire.com/file/cp58n9...ff+Jammer.xlsx

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6 years 1 month

Posts: 376

[USER="70376"]stealthflanker[/USER]

just 2 things I need to know before downloading your excel sheet. What is the typical radar pulse repetition frequency and pulse width used by radar? Is there a way to determine these based on other factors(in layman terms)? Either way can you give me an average estimated range for radar pulse repetition frequency and pulse width for modern aircrafts?

Lets also say theoretically https://ieeexplore.ieee.org/document/6217012 I have this ultra high resolution to distinguish someone's face from 400kms away. Does resolution effect the RCS of a target? For example I have a very high resolution SAR to see a 1m2 target from 400kms away on radar would ultra-high resolution give me the ability to see a smaller RCS target than this?

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8 years 3 months

Posts: 1,081


You can download the spreadsheet i made for above calculation here :
http://www.mediafire.com/file/cp58n9...ff+Jammer.xlsx

I made one for self protection. Download here: https://ufile.io/s72e3
5 Megawatt radar
10 Watt jammer
Target RCS: 0.01 m2
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Member for

8 years 6 months

Posts: 906

[USER="70376"]stealthflanker[/USER]

just 2 things I need to know before downloading your excel sheet. What is the typical radar pulse repetition frequency and pulse width used by radar? Is there a way to determine these based on other factors(in layman terms)? Either way can you give me an average estimated range for radar pulse repetition frequency and pulse width for modern aircrafts?

That depends on operating mode. Selecting what's necessary is actually a complex process involving many factors. The best one can do in layman's term is to find data for other radar and apply it.

The data however can be easily found in good forum such as Secret Project's avionics section. Or you can find it on books about radar. I also hosted a table containing modes of typical fighter radar which you can see typical PRF and pulsewidth used.

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Member for

6 years 1 month

Posts: 376

Thank you, sorry I edited the 2nd question. You do not have to answer it if you want.

Member for

6 years 1 month

Posts: 376

I swear this will be my last time asking a question regarding the AESA calculator. I do not know if its a user error on my part or this sheet does not calculate RCS distance when narrowing or widening beams.

https://www.webcitation.org/6Qpsm5PU...eek_010807.pdf

The F-22’s radar range is only [officially] described as being more than 100 mi. However, it’s thought to be closer to 125–150 mi., which is much further than the standard F-15’s 56 mi. radar range. New, active electronically scanned radar technology - optimized for digital output - is expected to soon push next-generation radar [the AN/APG77v1] ranges, in narrow beams, out to 250 mi.


The APG-77v1 with newer


GaAs

modules provides a range of 250 mi (400 km) or more; this is believed to be possible due to the use of more narrow beams
and can cue radar emissions to be confined to a


narrow beam

(down to 2° by 2° in azimuth and elevation) to increase stealth.

Even the Nebo-M with 360 degrees for a 1m2 target shows 480km but narrow the beam to 90 degrees that distance increases to 510kms.

Is it too much trouble to ask you if there is a possibility you could update an excel sheet calculating the RCS distance by either widening or narrowing azimuth radar beams(Or I just do not have the know how or its a screw up on my part)? For example I put 2000 T/R modules with 10 watts for modules, than put 1m2 for the target RCS, without changing the other properties(assuming this is the an/apg-77v1 calculations). So for horizontal beam I put 120 degrees, and vertical I put 12 degrees, 90% lock on I got 217kms. than narrowed the beam for both 2 by 2 degrees I got 179kms while the sources I have regarding the SU-35 and F-22 tell me if I narrow my beams I spot the same target more far away. Is there another calculation to do this in which you have for your sources, if so is it possible to update an excel sheet(while keeping it simple and stupid for users like me) by the use of narrowing beams and seeing targets more far away?

Member for

8 years 6 months

Posts: 906

I swear this will be my last time asking a question regarding the AESA calculator. I do not know if its a user error on my part or this sheet does not calculate RCS distance when narrowing or widening beams.


You can specify the scan sector easily in the sheet.

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Reducing scan sector however may help extending the range. But one must also consider the increasing amount of integration loss which will wash the range advantages.

Your sources also does not specify many things considered in the calculator. E.g they don't specify their detection probability. and dwell time (how long the beam stays in the search sector) So you can't really "re-create" the same condition mentioned in your source with the calculator.

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Member for

6 years 7 months

Posts: 156


I made one for self protection. Download here: https://ufile.io/s72e3
5 Megawatt radar
10 Watt jammer
Target RCS: 0.01 m2
[ATTACH=JSON]{"alt":"Click image for larger version Name:\tnum.png Views:\t0 Size:\t122.2 KB ID:\t3852204","data-align":"none","data-attachmentid":"3852204","data-size":"full"}[/ATTACH]

Target rcs from who?

From airplane which is jammed or Rcs from own airplane?

Member for

8 years 6 months

Posts: 906

Lets also say theoretically https://ieeexplore.ieee.org/document/6217012 I have this ultra high resolution to distinguish someone's face from 400kms away. Does resolution effect the RCS of a target? For example I have a very high resolution SAR to see a 1m2 target from 400kms away on radar would ultra-high resolution give me the ability to see a smaller RCS target than this?

Resolution helps you identify the target by distinguishing various parts of it and allow you to build imagery out of it. and no it does not affect target RCS.


Target rcs from who?

From airplane which is jammed or Rcs from own airplane?

It's clearly the target aircraft that do the jamming.
The equation for self protection jamming presented in the book assumes that the jammer can always be in the mainlobe of the victim radar e.g you're being locked. With this the jammer will always have the advantage of injecting its techniques which will not be/seldom noise but RGPO etc.

Target RCS have little meaning for self protection as it will always be lower in terms of magnitude of power compared to what being emitted by the jammer.

-----------------------------
Future works for AESA radar calculator :
-more refined path propagation
-signal processor, time to introduce what is pulse doppler or MTI.
-Clutter (Sea, Land, Rain)
-Auto PRF select (user no longer have to specify PRF, the sheet will generate it instead based on target velocity or some general requirement like 95% visibility etc) It will instead prompt user to select "High, medium or low" PRF

Evaluation of clutter and signal processor is rather bit complex and specific as it may require user to actually specify some variables like target speed. The radar equation for those can also be no longer closed term, but rather have to be analyzed iteratively. It will be somewhat like this in appearance :

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This is a simplified model i use to estimate detect ability of target in sea clutter for an anti ship missile. The simplified equation is used and as seen the target is detectable in sea state 0-4 (i skipped sea state 1 as the base data i use for the clutter model is inaccurate) With doppler or MTI processing.

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Above is the example of rain clutter evaluation , as seen i need to specify detection range first.

The way of implementation i envisaged atm is to actually use the detection range from the calculation and later "evaluate" it using the user supplied "Processor improvement factor" to see if the radar can detect the target at specified range. If it cannot detect it then the sheet will look into similar signal strength to range table as i provided in the first image, then give range value where the signal strength exceeded the required threshold which in this sheet i would assume to be the same as one in thermal noise environment.

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Member for

6 years 1 month

Posts: 376

[USER="70376"]stealthflanker[/USER]

Hate to be a bother but is there a possibility to make an excel sheet that tells you what RCS size there is in close or farther ranges? Example there is a 1m2 target at 400kms however if I lower that target to .0001m2 what range would it be or lets say I track a .01m2 target at 400kms away than what distance will I see a .0001m2 target at? Is this feasible to do? And if so do you have plans to make such a project and if not can you dumb down the equation regarding this task? Thanks if you do or if you know any other user that can do this.

Member for

8 years 6 months

Posts: 906

[USER="70376"]stealthflanker[/USER]

Hate to be a bother but is there a possibility to make an excel sheet that tells you what RCS size there is in close or farther ranges? Example there is a 1m2 target at 400kms however if I lower that target to .0001m2 what range would it be or lets say I track a .01m2 target at 400kms away than what distance will I see a .0001m2 target at? Is this feasible to do? And if so do you have plans to make such a project and if not can you dumb down the equation regarding this task? Thanks if you do or if you know any other user that can do this.

It's very hard to understand what you mean but i think i know. For attempt to obtain value of RCS based on detection range, one can simply run the 4th root rules in reverse for that.

Target RCS= (Reference RCS/Reference Detection range^4)*Target Detection Range ^4

Following is the example :

We have a radar with following capability :
Detection range for 3 sqm target : 250 km

A contact is detected at 50 km, what is the RCS of the target ?

Then we run it :

Target RCS= (3/250^4)*50^4
Target RCS= 0.0048 sqm.

Member for

6 years 7 months

Posts: 156

[USER="70376"]stealthflanker[/USER]

Hate to be a bother but is there a possibility to make an excel sheet that tells you what RCS size there is in close or farther ranges? Example there is a 1m2 target at 400kms however if I lower that target to .0001m2 what range would it be or lets say I track a .01m2 target at 400kms away than what distance will I see a .0001m2 target at? Is this feasible to do? And if so do you have plans to make such a project and if not can you dumb down the equation regarding this task? Thanks if you do or if you know any other user that can do this.

I have it, it is like stealthflanker tells.

Its simple, but i think it is what you are looking.

How do you want i send you the file?...inside this post do not let me upload xlsx extension

Member for

8 years 6 months

Posts: 906

just put it on google drive or some other filehosting service.

Member for

6 years 1 month

Posts: 376

Rall you are a great help but I will take stealth flankers calculation response. Thank you guys for being great resources.

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10 years 5 months

Posts: 2,014

[USER="70376"]stealthflanker[/USER] what do you think about this
pilot rate F-35 radar better than F-15C but worse than F-15E
Basically, APG-63 v3 < APG-81 < APG-82
But since APG-63v3 aperture is so much bigger than APG-81, shouldn't it is also better than Apg-81?

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24 years 2 months

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pilot rate F-35 radar better than F-15C but worse than F-15E
Basically, APG-63 v3 < APG-81 < APG-82
But since APG-63v3 aperture is so much bigger than APG-81, shouldn't it is also better than Apg-81?

That is based on the opinions of 2, in words two F-15C pilots. And it doesn't say if they compared APG-63 (V)1, (V)2 or (V)3.
Maybe they were simply impressed with A/G modes, easy feat.
7 F-15E pilots without info on the radar aswell. I wouldn't read too much into it.

Member for

8 years 6 months

Posts: 906

@mig31bm

Well we dont know what type of F-15E and C's being discussed. Plus im kinda late in news, Im curious on how many C and E's received the new APG-63V3/82's.

Aperture wise it's does look bigger, perhaps even better cooling especially the APG-82 Bird which receive cooling upgrades, might allow bit more powerful TRM to be used. Overall however it is kinda hard to judge which parameter is better from the qualitative presentation.

Member for

17 years 11 months

Posts: 1,010

Did you perhaps mean fourth power in your formula, instead of fourth root?