Register Free

Announcement

Collapse
No announcement yet.

AESA Radar range calculator.

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

    AESA Radar range calculator.

    Greetings. It's been a while since i post a thing here.. bit boggled with some IRL issues. But well here i come.

    So what i shared is, kinda small project of mine based on my interest toward radar.

    The AESA Radar range calculator here is an excel spreadsheet, made based on several books like SKolnik's 3rd Introduction to Radar system, Stimson's 2nd Edition of Introduction Airborne Radar and others.

    The calculator will attempt to predict radar ranges based on inputted variables and taking account of some important things that for some reason not considered by other calculators like pulse integration, scan sectors and most importantly the antenna weighting scheme.

    As we know AESA Radar or perhaps even its Hybrid Array sibling like N011M Bars is capable of actually altering its radiation pattern, based on algorithms like Taylor, Cos, Hamming. etc. Even special algorithm has been developed for AESA. The change in radiation pattern allows reduction in sidelobe, beamwidth optimizations, or even total split of the aperture into several smaller one for search. In cost of efficiency and angular resolution.

    This calculator however are still what you call as "Noise limited", basically it's not taking account things like ground clutter or weather. However i think for case like high altitude combat, it's good.

    It has simple interface and i believe quite easy to understand.

    Click image for larger version

Name:	esa_feature_by_stealthflanker-db04d9s.png
Views:	1
Size:	116.2 KB
ID:	3731792


    The download link.

    http://www.mediafire.com/file/s8ea52...able.xlsx/file

    critics and suggestion are welcome.
    Last edited by stealthflanker; 21st August 2018, 08:44.

    #2
    Very detail , i love it.

    Comment


      #3
      Great work.. congrats.. far more advanced and detailed that I could ever have gathered together..

      one thing if I might ask.. is it possible to upgrade a radar with an antenna of a certain aperture and certain amount of elements by replacing the antenna with a different one with larger TRM count? Say your APG-77 has 2,000 TRMs, today, could it get a 2,700-TRM array one day? I am quite sure that the R&D and technology enable to pack the TRMs into tighter space, but ain't the physical dimensions of the emitter/receiver limited/dictated by the respective radar band?

      thanks

      Comment


        #4
        AFAIK, Too narrow spacing between T/R modules may cause the system to have bad overheat or mutual coupling

        Comment


          #5
          Looks great.

          What are the parameters which control beamwidth? I always taught about a AESA that concentrates the RF energy via resonance and hence achieves greater ranges. At some point the amount of airspace electronically scanned would increase the time for a complete scan of the hemisphere too much. But for specialized purposes such as target illumination, could the beamwidth be significantly improved compared to a PESA?

          Thanks.

          Comment


            #6
            Originally posted by PeeD View Post
            Looks great.

            What are the parameters which control beamwidth? I always taught about a AESA that concentrates the RF energy via resonance and hence achieves greater ranges. At some point the amount of airspace electronically scanned would increase the time for a complete scan of the hemisphere too much. But for specialized purposes such as target illumination, could the beamwidth be significantly improved compared to a PESA?

            Thanks.
            The beamwidth of the AESA is directly controlled by the number of its elements, which govern the physical dimension of the antenna. Weighting algorithm can later be introduced to control radiation pattern. However one cannot really make beam narrower unless the antenna is enlarged.

            In the calculator the basic equation to calculate beamwidth is :

            Click image for larger version

Name:	The beamwidth.png
Views:	1
Size:	1.8 KB
ID:	3673626

            The resulting beamwidth is later multiplied by the "Beamwidth factor" or "K" from the tapering algorithm drop down menu.

            Originally posted by MSphere View Post
            Great work.. congrats.. far more advanced and detailed that I could ever have gathered together.

            one thing if I might ask.. is it possible to upgrade a radar with an antenna of a certain aperture and certain amount of elements by replacing the antenna with a different one with larger TRM count? Say your APG-77 has 2,000 TRMs, today, could it get a 2,700-TRM array one day? I am quite sure that the R&D and technology enable to pack the TRMs into tighter space, but ain't the physical dimensions of the emitter/receiver limited/dictated by the respective radar band?

            thanks
            Apparently that's the plan for US AMDR Radar, where they have some sort of "common module" block. So what you need to "upgrade" is Physical space. For fighter radar tho, i am not so sure as the space and power generation there is very premium.

            There is of course another consideration of using less modules than what an antenna can actually accommodate like cost or RCS reduction, from edge treatment. Other possible consideration is cost as we know TR module is still an expensive item. Cost issue become critical if you desire to use higher frequency (say 94 Ghz AESA) and wish for a full array. you would need thousands of modules.

            Anyway related to cost, i included a small chart depicting several factor and their relations to wavelength. As you see cost increase exponentially when you move to higher frequency (shorter wavelength)

            The size of the AESA T-R module is governed by physics. The width is the primary dimension, where it need to be about half wavelength. So for X-band the module's width would be about 1.5 cm for 3 cm operational wavelength. Technology can only goes as far as packaging, cooling and materials.


            Originally posted by garryA View Post
            Very detail , i love it.
            Thanks a lot.
            Attached Files
            Last edited by stealthflanker; 20th March 2017, 22:16.

            Comment


              #7
              Updates

              Slight updates to the calculator. The Required SNR variable is now automatically calculated by the spreadsheet.

              The Calculated SNR is for Swerling 1 or 2 target. Representative for maneuvering fighter aircraft, and basically the goal of any fighter/tracking radar designer (as making the target behaves in swerling 2 will reduce the required SNR)

              As you see no more SNR variable.
              Click image for larger version

Name:	screenshot_1_by_stealthflanker-dblkr0p.png
Views:	1
Size:	115.4 KB
ID:	3676406

              Instead it's become part of the calculated variable. The calculated SNR is for 90% probability of target detection. Which allows lock on. Thus the R90 in the bold coloumn is the range where target could be locked on by the radar and later fired upon by the radar platform.

              Click image for larger version

Name:	screenshot2_by_stealthflanker-dblkr0n.png
Views:	1
Size:	114.4 KB
ID:	3676407

              The range coloumn
              Click image for larger version

Name:	screenshot_3_by_stealthflanker-dblkr0h.png
Views:	1
Size:	109.1 KB
ID:	3676408

              The R50% is the range where target detection probability is 50%. Such range is where radar might detect and track the target But not having the confidence of locking it for weapon system employment. It may however be used to cue other fighter aircraft or higher resolution sensors to establish more confidence on what being detected, is it real target or just false alarm.

              Comment


                #8
                So many variables iam overwhelmed with choices.

                Comment


                  #9
                  what do you mean @moonlight ?

                  Comment


                    #10
                    for laymen it would be easier if there were just several choices, and everything else was approximated (average and/or generic values used), even if it meant significantly greater errors.

                    Anything other than these variable might confuse most people: output power, antenna diameter, target RCS, wavelength.

                    Comment


                      #11
                      @totoro Thanks for the input.

                      Let's see what i could do. Using approximations is good however the calculators may lost its flexibility. and some variables like PRF can't really be "automated" unless locking the calculator in specific frequency (say X-band) But we will see.

                      Comment


                        #12
                        Improvements time. Trimming down some variables and Provide pre-calculated one. The calculator basically remains the same BUT hopefully it's more user friendly.

                        Click image for larger version

Name:	opener2_by_stealthflanker-dblxpfk.png
Views:	1
Size:	122.2 KB
ID:	3676427
                        The cover page now feature less clutters and lesser amount of input. Unfortunately as i said previously, pulsewidth and PRF cannot really be "automated" as it depends on the radar mode. Eliminating them will essentially locks the functionality of the calculator to X-band. While we know Russian developed L-band leading edge radar. and we have AEW AESA radar such as APY-9 and Elta Phalcon.

                        For filling guide for PRF and pulsewidth however. One can consult to following table, genereously provided by Carlo Kopp in Radar Handbook 3rd Edition. For both A2A and A2G modes

                        A2A


                        A2G



                        The second page of the calculator contains the pre calculated variables. One may still edit them. However it could be left as is. The pre calculated variables are based on generic information provided by radar literature in my possession.

                        Click image for larger version

Name:	trial_version_2_by_stealthflanker-dblxoon.png
Views:	1
Size:	113.8 KB
ID:	3676428

                        Hopefully it could be more useful and easier to use. However feedback and input are appreciated.


                        Download link for the Improved version :

                        https://www.mediafire.com/file/7wrky...CalcTrial.xlsx

                        Comment


                          #13
                          is it possible to upgrade a radar with an antenna of a certain aperture and certain amount of elements by replacing the antenna with a different one with larger TRM count?
                          Unless the modules were larger than half wavelength for some weird reason, the answer is no.

                          If you tried to space the modules closer than lambda/2, you'd end up with multiple beams going in different directions. Not very useful for a radar.

                          Comment


                            #14
                            VERY complicated, but certainly not impossible AFAIK, changing time shifts no?

                            lambda/2 is linked to 60 value isn't it?

                            Comment


                              #15
                              If you tried to space the modules closer than lambda/2, you'd end up with multiple beams going in different directions. Not very useful for a radar
                              AFAIK, lambda/2 rule is for upper limit rather than lower limit. Lambda/2 spacing give the best gain though IMHO

                              Last edited by garryA; 2nd September 2017, 09:53.

                              Comment


                                #16
                                What gain ?

                                Anyway Lambda/2 spacing from image above give scanning without grating lobes. Any other spacings be it less or more should have other consideration on choosing like say economy. The risk associated by using other form of spacing for ESA elements are limited steering angle. One example is ESA modules in TOR-M1 system which have wide spacing of lambda*3. The Russian designer opted such scheme for economy while providing best aperture area and gain possible. Whle accepting electronic steering angle of only 7 degrees.

                                Other possible reason for choosing non half wavelength scheme is stealth as to reduce bragg lobes. Bragg lobes

                                Comment


                                  #17
                                  @stealthflanker:
                                  I mean there are too variables so i don't know what to choose to calculate range. For example: I want to estimate air to air range of radars like APG-77 and APG-81. But i have no idea what to put in Doppler filter per band or system loss budget. Even pulse width is hard for me to decide, especially with technology like pulse compression. Basically what said by totoro.
                                  Last edited by moon_light; 2nd September 2017, 14:29.

                                  Comment


                                    #18
                                    I want to estimate air to air range of radars like APG-77 and APG-81
                                    I gave it a shot:
                                    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 search volume.
                                    Scan volume: 20 azimuth, 10 elevation (Cued search => longer dwell time => longer range)
                                    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
                                    Last edited by mig-31bm; 5th September 2017, 06:07.

                                    Comment


                                      #19
                                      When I reduce the radar scan sector angles I would expect a rather proportional increase of detection range, but sometimes there is even an decrease. Is the aperture gain included in the spreadsheet so that there is a limit from which on no increased detection range can be achieved by confining the scan angles?

                                      Comment


                                        #20
                                        The limit lies in the pulse integration loss. Not all of them can be integrated by the radar, and thus integration loss occurred. This in radar range equation will actually increase the required signal energy for target detection.

                                        Comment


                                         

                                        Working...
                                        X