AESA Radar calculators

I hosted this in another forum :
https://forum.keypublishing.com/showthread.php?141862-AESA-Radar-range-calculator

Sparked nice but kinda short discussion, which kinda sad given alot of enthusiasm toward this type of antenna.

Anyway This simple calculator will help range modeling of 2 types of AESA radar. The planar array which is the one can found in aircraft nose or large AEW aircraft ala A-50EI,JSTARS, Phalcon and SAAB Erieye/Global Eye. And linear array which can be found in NIIP's new radar. The user interface is very simple, as simple as it can get and allow prediction of range in 50% and 90% probability. Ranges where usually volume search and tracking/locking on target is defined.

The interface :3

Selectable antenna type.


Dwell time for the antenna, basically determine how long it will search the sector.


and some attempt to model weather tho this one is likely improper. Derived from simplified K.Barton's model.



I recommend to leave it as is as it might cause problem.

My latest post in the original thread contains some discussion material if one interested or wish to model low RCS target especially to determine what value should be used for frequency other than X-band.

https://forum.keypublishing.com/showthread.php?141862-AESA-Radar-range-calculator&p=2452967#post2452967


Download Link.
http://www.mediafire.com/file/s8ea52zoc8zzf17/AESACalcStable.xlsx/file

Thanks stealthflanker  

LMFS wrote:Thanks stealthflanker  

you're welcome

Updates and stuffs.

New sheets :
1.Target RCS conversion.
This kinda controversial sheet will attempt to approximate/predict RCS of a target and establish a lower and upper limit of its RCS based on Wavelength and Squared wavelength phenomenon.



As discussed in following post :
https://forum.keypublishing.com/showthread.php?141862-AESA-Radar-range-calculator&p=2452967#post2452967

It based on my own observations. So it goes without saying to treat the result carefully and as a first order of approximation.

2.Antenna Module Finder
How many TRM/radiator an AESA radar can have ? You can quickly find your answer by using this sheet



It also include simple calculator to find area of most commonly used antenna.

3.New Antenna
This new antenna is basically same as planar array BUT with take factor of antenna dimension. Provision of this antenna in option is necessary due to the fact not every AESA antenna are regular (box or circle) but like Su-57 N036 Antenna or Chinese KJ-2000 AWACS antenna, they are eliptical and therefore need a separate section.



Another update is the replacement of wavelength with frequency, so user only need to input frequency in MHz instead of wavelength.

Update.

Download link :
http://www.mediafire.com/file/s8ea52zoc8zzf17/AESACalcStable.xlsx/file

Adding Multipath propagation as factor.

The multipath or path propagation factor is kinda rarely discussed in typical open forum. The importance however is paramount that it will directly affect design of the rada and must be considered for performance calculation. The path propagation factor will also affect observed radar cross section of the target. The result is a variable called "Effective RCS". The free space RCS (that is the one not affected by path propagation factor) multiplied by the path propagation factor.

The importance of the effective RCS lies in the fact that it's very specific for the type of radar, it's target behavior and the surrounding environment. Change in target altitude, radar antenna height will dramatically change the effective RCS, as illustrated below.

VHF Band.


X-band


Notice the change of RCS from range as the target basically "move" from one lobe to the other and also change of altitude. Thus attempt to calculate RCS based on non instrumentation radar like say old discussion in SAM system simulator forum regarding F-117 RCS, must include the path propagation factor. Otherwise the resulting measurement (0.001 sqm in 30 Km) is NOT usable in other form of VHF radar and in other environment.

The propagation factor itself is a product of interaction between reflected RF energy from target with its surroundings. The resulted interaction creates interference, be it constructive which will increase the signal strength or destructive which would weaken the signal. It also affects radar coverage, creating the well known "lobing pattern" as seen in typical range-height coverage diagram for a ground based radar



In this AESA radar calculator however the model of the path propagation factor is rather simplified model where it use Flat earth approximation and perfectly smooth and reflective surface. Arguably however this is similar to sea water. More complex modeling however have to wait until i can solve problem related to implementing antenna radiation pattern in excel. More accurate modeling of path propagation factor requires antenna radiation pattern in elevation to be known.

User can enable or disable the calculation of path propagation factor via simple drop down menu.



User can then specify the height of the target and height of his radar antenna.

The result section now contain not only range but also the calculated path propagation factor and effective RCS.

It's been quite a while.

The following is the latest iteration of the AESA Radar Calculator :

DOWNLOAD LINK. VER 3.

So what's new in the calculator ? :

Fixes :
1.Fixed the inconsistent unit in the calculation of detectability factors. Despite giving "reasonable" result, this actually may lead to erroneous calculation.

2.Improving the atmospheric factors, now the target altitude are used to calculate the elevation angle which then become input to the atmospheric absorption factor

3.Cutting down of the unnecessary pages, as apparently users are not really interested in additional tools such as RCS conversions (This one is partially integrated in the main sheet now) or tools to estimate limitation of radiated power based on cooling capacity.


New Features :
1.Custom Dwell time :

In previous edition, user are constrained in terms of selection of available dwell time for its respective radar. a Feature is added to allow custom dwell time to be inputted. So after user selects the dwell time in the respective drop down menu, if custom dwell time option is selected. User can then proceed to input the desired dwell time in the coloumn after the selection box.




2.Custom Detectability Factor
User can now choose to allow the sheet to estimate the detectability factor (SNR) Or manually input the value by him/herself. By default it selected to Yes.




3.Result page.
Yeah so basically this displays the result of the calculations, since this calculator originally made for fighter aircraft radar, it is therefore using the airborne radar as parameters. The sheet's calculation have been adjusted that it allows comparison of radar works in different band (e.g L band vs X-band)



The range performance is presented in 3 categories based on the "level of confidence" Which is 50% (R50), 90%(R90) and Instrumented. The 50% probability of detection indicates the presence of a contact with 50% probability it's a "real" contact or ghost. Old NIIP Thikomirov site presented their radar data in this level of confidence. 90% Indicates higher threshold of detection/ high SNR, meaning that the target at that range is "90% a target" At this level of confidence the radar may begin process such as tracking or engagement/locking target with weapon systems. The Instrumented range is the range where the radar is "allowed" to "announce" detection. The value is about 20% of the maximum detection range. In this sheet it is assumed to be 20% of the R50, for increased "confidence" of a detected contact.

The "benchmark" fighter radars presented in the result sheet is based on open sources, APG-63V2, APG-79 and APG-83 however are estimated with ideal assumption (The platform is "matched" with the radar) Thus my overestimate the detection range value. All the range values are for 90% probability of detection. Given that there are no real disclosure on the assumption of detection probability for the radars i decided to make assumption that all the range values from the open source materials are for 50% probability of detection, thus needs to be "normalized" to 90%. To do that i first made estimate of SNR using the simple approximation provided in R.G Curry's "Radar Essentials" on SW1 target, which yield SNR value for respective detection probability (50% and 90%) The detection range can then be simply estimated by 4th Root using SNR as value. The result is estimate of the R90. eg Irbis-E with claimed detection range of 400 Km for 3 sqm target, in 90% it becomes 225 km.

This section is probably can be edited out if necessary. but yeah i feel it's needed

Some appeal:

Stealthflanker wrote:This calculator has been under development since 2015. It was at first to mainly satisfy my curiousity toward range estimation for a radar and what factor saffecting it. There is however another purpose, which basically to "escape" from at least some difficulties of my real life. Trying to make my 3D modeling hobby as a living, enjoyable but the income is not steady especially now. That my clients are apparently more concerned on surviving and therefore i received no income. Finding steady job is difficult here in Indonesia. So yeah. If you found this calculator helpful.. Maybe a little bit of donation to help me at least taking off the edge. it could be send through paypal at ffcconcept@yahoo.co.id.

StealthFlanker, thanks for sharing this calculator. I would certainly like to contribute but Banks here in India are working with just a few employees because of the Lockdown so several net banking features like PayPal are not working right now.

On a separate note, since you are seeking donations, why don't you convert this calculator into an app and launch it on a site like Product Hunt. You can create a brief demo for it.

Then you can add Pricing to it. Probably add a few more features. And then anyone who downloads this app needs to pay say US$5 for downloading it.

Sujoy wrote:
StealthFlanker, thanks for sharing this calculator. I would certainly like to contribute but Banks here in India are working with just a few employees because of the Lockdown so several net banking features like PayPal are not working right now.

Thank you for the kind words Sujoy

Sujoy wrote:
On a separate note, since you are seeking donations, why don't you convert this calculator into an app and launch it on a site like Product Hunt. You can create a brief demo for it.

Then you can add Pricing to it. Probably add a few more features. And then anyone who downloads this app needs to pay say US$5 for downloading it.

It would be nice, tho i feel that it wont be fair as my calculator already been featured in a research paper and it's for free.

https://www.matec-conferences.org/articles/matecconf/abs/2019/53/matecconf_easn2019_04001/matecconf_easn2019_04001.html

I imagine it would be inconvenient for people to suddenly have a paywall.

But yeah. hope i can survive the coding learning phase to have a proper app/executables for it.