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  • stealthflanker
    Rank 5 Registered User
    • Sep 2015
    • 1027

    #61
    Which essentially bring us back to square one. No matter, i will push forward. see what i could dig up later.

    Perhaps approach using cost break down of typical AESA would yield better result. Then again price may differs. So the result would likely differs by some margin.

    Comment

    • bring_it_on
      2005-year of the RAPTOR!!
      • Jun 2004
      • 12480

      #62
      Performance also contributes since some radars require a lot of support equipment as part of them. The AMDR contracts would cover ancillary and cooling footprint while the TPS-80 is air-cooled but comes with a trailer and other recurring hardware essential to the warfighter but not linked directly to the radar side or its RF components. You would need detailed BOMs to get to the bottom of this. Things get even more complicated when the OEM is essentially an integrator such as a Lockheed or a SAAB that is sourcing equipment form multiple suppliers that have their individual component BOMs and profit margins. At least with the likes of AMDR and TPS-80, majority of the organic components (at least the most expensive RF ones) are produced by the Prime but in case of the Space Fence, the 50K+ T/R modules are coming form a different supplier (iirc Cree) while other components are being produced by Lockheed. Needless to say, this will be proprietary information EXTREMELY closely guarded for competitive reasons.

      When you get into GaN, TRL and MRL numbers matter despite marketing and PR claims of a number of suppliers that they can produce and have something on the test set up. When you require X,XXX to XX,XXX GaN RF components a year, your mastery of manufacturing and the technical capability absolutely matters as far as yields and ultimate production cost is concerned. Contrary to marketing spin, this is not a level playing field when you get down to individual foundries or integrator primes.
      Last edited by bring_it_on; 11th October 2017, 12:54.
      Old radar types never die; they just phased array

      Comment

      • stealthflanker
        Rank 5 Registered User
        • Sep 2015
        • 1027

        #63
        I think this should suffice for now.

        Click image for larger version

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        Comment

        • RALL
          Rank 5 Registered User
          • Aug 2017
          • 215

          #64
          Good job, Man!!!

          Comment

          • PeeD
            Rank 5 Registered User
            • Dec 2003
            • 132

            #65
            @swerve

            Erieye-ER (one customer so far) has S-band GaN modules. I think the Erieye antenna is 8 x 0.6 metres, so about the same as your 2x2 metres. Dunno how many modules, though, or what power.

            The GaN modules are said to give a massive increase in detection range of VLO objects. Maximum range against big, high RCS things such as ships is still the horizon.
            I still have doubts about the high performance calculated by stealthflankers spreadsheet but if there is no mistake, it now makes perfect sense why some countries like Sweden go for S-band. Its not only economical but would have a high capability against LO up to VLO assets.
            SiC, silicon and GaA are all able to provide a 50W peak power per element, no strict need for advanced and expensive GaN modules.

            If there is no tight space restriction, a 6000 element array with low cost 50W elements provides the same range performance as a 3000 element, state of the art GaN 400W array.
            Thanks to stealthflankers sheet, this now becomes visible. As well as the extreme performance even lower power 50W non-GaN S-band TRMs can develop, exceeding line of sight endo-atmospheric range against any conventional target and providing stand-off EW range counter-VLO capability or/and burn-trough capability in heavy jammed environment.

            It now also makes sense why Russians skipped the Gamma-D radar and went for the Gamma-S, as its high power is sufficient to compensate better counter-VLO performance of L-band. On the other hand, you can't achieve power levels of 50W without more expensive GaN modules in higher bands such a X-.

            But I still don't know if PW of 100s and PRF of 2khz would be applicable for such early warning radars as those data are only derived from that TRM datasheet I posted. I still would like to know what PRF and PW levels are common for VHF- to X-band radars in search mode or illumination.

            Comment

            • stealthflanker
              Rank 5 Registered User
              • Sep 2015
              • 1027

              #66
              You can try Radar tutorial's database

              One example for your interest would be the Seek Iglo
              http://www.radartutorial.eu/19.karte...rte007.en.html

              Example of VHF band.
              http://www.radartutorial.eu/19.karte...rte049.en.html


              Selection of PRF for early warning radar band will usually be much lower compared to higher band radar (X etc) Mainly because tradeoff between doppler and range ambiguity.
              ----
              For X band and higher we may have several different PRF. a fighter radar may have like 10-11 PRF. Consist of 1 Low PRF mode for SAR or MTI, 8 for Medium PRF mode, 2 would be high PRF for Velocity search.

              Comment

              • mig-31bm
                Rank 5 Registered User
                • Oct 2013
                • 2110

                #67
                Originally posted by PeeD
                providing stand-off EW range counter-VLO capability or/and burn-trough capability in heavy jammed environment.
                The table is strictly in no jamming environment.

                Originally posted by PeeD
                I would expect half wavelength spacing, hence a 2x2m array @ 4000 elements,
                S band with 15 cm wavelength (2Ghz).
                4000 elements=> 64 vertical and 64 horizontal lines
                If the aperture is square then its length 64152 = 480 cm or 4.84.8 meters with half wavelength spacing.

                S band with 11.5 cm wavelength (3Ghz) need 3.63.6 meters array for 4000 elements.
                Last edited by mig-31bm; 12th October 2017, 12:58.

                Comment

                • PeeD
                  Rank 5 Registered User
                  • Dec 2003
                  • 132

                  #68
                  @stealthflanker

                  Thanks, yes I also found those data from radartutorial to model my VHF and S-band radars with you spreadsheet.
                  For the PW of VHF-band radars it seems to have been greatly increased in state of the art radars. Phase shift keyed signals are claimed to be 42*6s for this P-18 upgrade: http://www.litak-tak.eu/en/products/radars/p-18ml/

                  If I have interpreted it right it would result into an effective 252s pulsewidth. Hence the performance of an AESA solid state P-18 would be more than double for the same peak power (speaking of Nebo).

                  Then also the huge possible pulsewidth of 800s for the AN/FPS-117 creates some confusion. But for low PRF it should be possible at max. duty cycle.

                  @mig-31bm

                  Jamming is not included, but the very high performance of large S-band arrays would not only be effective against VLO targets, but also increase the burn trough performance when jammed. Hence the range performance is a direct indicator for counter-VLO and (non-ECCM) counter-jamming performance.

                  You and stealthflanker are of course right about the array size. It is about 3,6m x 3,6m for 4000 TRMs and just 1600 for a 2m x 2m array.

                  However even those "just" 1600 S-band low power 50W elements would have a ~230km detection range against a 0,001m target. This could easily mean that a VLO asset with a X-band performance of 0,0001m would be detected at 230km stand-off range by that 2m x 2m array, in case the RAM/RAS (or also shaping) performance is decreased by 10dbsm @ 3Ghz.

                  I'm surprised by those performance levels. To some extend it changes the view that L-, UHF-, and VHF-band assets are the best approaches for counter-stealth. Use brute force of a cheaper TRM technology (non-GaN, 50W, possibly air cooled tile modules) and with a large enough array, you get the job done at a much higher position accuracy.

                  Comment

                  • bring_it_on
                    2005-year of the RAPTOR!!
                    • Jun 2004
                    • 12480

                    #69
                    I think this should suffice for now.
                    This is something more recent...
                    Attached Files
                    Old radar types never die; they just phased array

                    Comment

                    • RALL
                      Rank 5 Registered User
                      • Aug 2017
                      • 215

                      #70
                      very Good Job @Stealthflanker

                      Comment

                      • stealthflanker
                        Rank 5 Registered User
                        • Sep 2015
                        • 1027

                        #71
                        Thanks, Rall.

                        -------------
                        A little update regarding the calculator and some additional thoughts.

                        The fixed-version

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

                        The fix mainly deals with confusion regarding finding the number of beams and determination of dwell time for linear array. The previous version is unfortunately using conventional volume search equation where the radar Had to have elevation beam scanning. Something which linear array doesn't have. I deliberately delayed Moonlight's suggestion few pages before to find better reference instead on relying on my own decision (as the excel calculator itself already contained perhaps many of my own decision, especially the weather tab which essentially a cheat and even simplified version of K.Barton's model instead of more proper L.V Blake model, but i haven't able to find way to implement in excel).

                        In this version the equation for the linear array is derived from one found in the book "Air and Spaceborne Radar an Introduction". French Radar book which all Rafale/Mirage enthusiasts must already know about.

                        The basic equation :
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                        Where Te is the Dwell time while 20 seconds is the time frame to search the area, 360 deg is the scanned area (which in spreadsheet reduced to 120) and 1.2 Degrees is the scanning azimuth beamwidth. Since the dwell time is already known (selectable from the user interface) One now only need the beamwidth and scanning area to find the appropriate answer.

                        Given the emergence of Linear array radar, like NIIP L-band, E-2D Hawkeye, Chinese Recconaissance UAV and US Joined-wing AEW concept. The ability to predict radar range of these arrays become important, not only for "serious" application but also general enthusiast who wish to "get to know" how these arrays might perform. A word of caution however is that the spreadsheet is only for sector scan radar not for rotating one. So if you wish to predict range for E-2D Hawkeye radar, assume that the rotodome is stopped and the radar would be in sector scan mode.


                        Another food for thought i would like to present is the Radar Cross Section variable. This topic is admittedly very complex yet unavoidable if one wish to actually make better guesswork on radar performance. The big question is "What RCS value i have to fill for the variable ?". Given the multiple dependence nature of RCS. 0.001 sqm in one frequency would not be valid in another and one may not always have access to more complex modeling or information. Especially if one wish to do the assessment for low observable target.

                        As we know that there is wavelength dependency of RCS, i concentrated my efforts towards it. The "Radar Cross Section 2nd Edition" book by Knott and Tuley had the squared wavelength dependency, which need to be understood as base. It turns out that the dependency is basically a base 20 Logarithm of the frequency in question subtracted by the "target frequency". Example of use.

                        We have an object designed to have 0.001 sqm or -30 dB RCS in 3 cm wavelength, what's the likely RCS in L-band of 24 cm ?

                        We first do some logarithm works :

                        The 3 cm band (0.03 m)

                        20*LOG(0.03) = -30

                        Then the 24 cm band (0.24 m)

                        20* LOG(0.24) = -12

                        The we subtract the first band with second one. Thus. -30-(-12)=-18 Now we see the 18 dB difference. We can further subtract the RCS of the object in dB with the resulted value from our first equation.

                        RCS in L-band= -30-(-18)
                        RCS in L-band = -12 dB or 0.06 Sqm.

                        There are however always an exception as one cannot generally use the squared wavelength dependence on all stealth objects. As described in following papers :

                        https://www.scribd.com/document/3846...haracteristics

                        and for those who interested in promises and features of low frequency radars the 2nd part of the paper
                        https://www.scribd.com/document/3846...d-Applications

                        The squared wavelength dependence appears to only applies toward conical object or ogival, which would make it suitable for predicting missile weapon RCS. Other military systems which does not exhibit such shape might follow wavelength dependence (which if one interested can be run down with same procedure i described BUT using 10 as multiplier instead of 20).

                        and now the question is "Which dependence i should use to fill ?" This is mostly based on my own simple observation. Based on what was available, especially with this famous image, courtesy of secretprojects.

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                        The object with many facets (the lockheed Have Blue) appears to follow the squared wavelength dependence while the Northrop XST which incorporates some curvi-linear elements (This feature would be observed in subsequent stealth fighters and missiles like YF-23A and B-2). One can see the dependence from the difference of RCS between high band (the X-K band) with the one in the lower 175 MHz band. The faceted have blue have 30 dB more RCS which quite close to the squared wavelength approximation (which put 34-39 dB of difference) The Northrop XST in other hand have 8 dB of difference which close to wavelength dependence (the procedure will give 17 dB of difference which basically 50% more).

                        This is admittedly subjective and would cause confusion. As there is no real measure to "see" how faceted or curved an objects are.

                        Another thing with the procedure i described above, one may find the conventional target to have "lower" RCS value in low band radar. Say 3 sqm fighter in X-band become 0.04 Sqm in L-band. This is not because the fighter is stealth, but it can be explained by simple antenna-beamwidth relationship. If we take aircraft as simple plane and expose it to radio signal of increasing wavelength, one might observe that as the wavelength grow, the reflected power would be weaker (thus lower RCS) One can see this in real life measurement of conventional aircraft RCS.

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                        Further observation or suggestion however is appreciated.

                        My other observation toward shapes however still suggest that somewhat, even curvilinear shape can still follow squared wavelength dependency. This is the aircraft based on Tacit Blue. Frontal area RCS on multiple frequencies.

                        The aircraft :
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                        RCS in Multiple frequencies.
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                        Notice the 25 dB diffrence between X band and the VHF band.

                        My take on the matter however is to use both wavelength dependence to establish "best and worst" case approximation of the RCS of the object. Where the wavelength is best case and squared wavelength serve as worst. Then calculate detection range based on both values in the spreadsheet to generate possible detection range.

                        Suggestions and critics are welcome. It's indeed complex and controversial topic. But as i said before unavoidable if some realistic range figure/number have to be found.

                        Comment

                        • stealthflanker
                          Rank 5 Registered User
                          • Sep 2015
                          • 1027

                          #72
                          Latest Version :

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


                          What's new ?

                          The addition of :

                          1.Target RCS conversion tool.
                          Following my thoughts on the above post, i decided to add the RCS tool into the spreadsheet to facilitate user to predict the upper and lower limit of RCS of his target.



                          2.TRM/Radiator module finder
                          This new sheet will attempt to predict the number of TRM an antenna can have, based on assumption of half wavelength spacing and fill factor. The antenna fill factor determines how many modules will occupy the antenna face. 100% indicates that the antenna face is filled with TRM. This might also reflect the technology and considerations during the design of the radar. e.g module dimensions. Current trends apparently moving toward tiled architecture due to simplicity of assembling and the fact that one can utilize most of the antenna area.



                          This spreadsheet also contain simple antenna area calculator to allow quick prediction of area of common antenna.

                          3.New antenna.
                          Given that not all AESA radar are built in axisymmetrical antenna (e.g KJ-2000 AWACS) New type of antenna and subsequent supporting variables have been added in the main sheet.



                          Should the new antenna selected, user can input the dimension of the antenna beside the number of module it have. Should other antenna type selected the width and height variable will be ignored during the calculations.

                          Another addition is the "scan time" in the result section.


                          The scan time/update rate is provided to facilitate user to view how fast the radar scans its assigned sector and relate it to range. Faster scanning may yield shorter range but rapid update suitable for mid-course update of a guided missile or vectoring interceptors, while long scans would be beneficial for detection of low RCS target.

                          Critics and suggestions are welcome , Thanks.

                          Comment

                          • garryA
                            Rank 5 Registered User
                            • Dec 2015
                            • 1120

                            #73
                            First and foremost, thank you for spending your valuable time making very details calculator for us.


                            Originally posted by stealthflanker
                            1.Target RCS conversion tool.
                            Following my thoughts on the above post, i decided to add the RCS tool into the spreadsheet to facilitate user to predict the upper and lower limit of RCS of his target.
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                            1-This isn't a big issue but i think it will be easier to use if you let the user input frequency in Ghz instead of Wavelength in meters.
                            2- I think the estimation of RCS difference might still be too big, at least for VLO aircraft.
                            Recently re-surfaced video (posted by mig31) indicate that at distance of 30 km, P-18 can't detect F-117 with 3 out 4 of its frequency setting.

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                            Rough extrapolate from the table
                            If radar height was 6.35 meters, P-18 will detect targets with RCS= 2.5 m2, cruising at 6km altitude from 132.5 km, reduce RCS by 10 times and we get 44% detection range reduction so F-117 RCS is smaller than 0.025m2 at frequencies >140 Mhz.
                            If radar height was 10.35 meters, P-18 will detect targets with RCS= 2.5 m2, cruising at 6km altitude from 180 km, reduce RCS by 10 times and we get 44% detection range reduction so F-117 RCS is smaller than 0.0025m2 at frequencies >140 Mhz.
                            Last edited by garryA; 21st August 2018, 08:52.

                            Comment

                            • stealthflanker
                              Rank 5 Registered User
                              • Sep 2015
                              • 1027

                              #74
                              1-This isn't a big issue but i think it will be easier to use if you let the user input frequency in Ghz instead of Wavelength in meters.
                              2- I think the estimation of RCS difference might still be too big, at least for VLO aircraft.
                              Recently re-surfaced video (posted by mig31) indicate that at distance of 30 km, P-18 can't detect F-117 with 3 out 4 of its frequency setting.
                              1.I agree thanks. Although i think MHz would be better.

                              2.As i mentioned at post predating the update post. The approximation works best for simple shapes, though my observation suggest that it might be applicable to real aircraft. That is of course limitations which i assume the user would be aware of. It may over-predict the possible RCS value. The problem is of course i haven't able yet to find a good "fudge factor" to take account of such uncertainties. Lowering the dB value based on the XST image might work but will it be applicable to any other object ?. Thus why i release the sheet as is.





                              Rough extrapolate from the table
                              If radar height was 6.35 meters, P-18 will detect targets with RCS= 2.5 m2, cruising at 6km altitude from 132.5 km, reduce RCS by 10 times and we get 44% detection range reduction so F-117 RCS is smaller than 0.025m2 at frequencies >140 Mhz.
                              If radar height was 10.35 meters, P-18 will detect targets with RCS= 2.5 m2, cruising at 6km altitude from 180 km, reduce RCS by 10 times and we get 44% detection range reduction so F-117 RCS is smaller than 0.0025m2 at frequencies >140 Mhz.
                              Do you have any suggestion on possible fudge factor ?

                              Your extrapolation however i found rather complicated mainly because it requires vertical coverage diagram and taking account of multipath. These would make it hard to apply any result of the extrapolation in other radar, which may have different lobing structure on its vertical coverage.
                              Last edited by stealthflanker; 21st August 2018, 11:53.

                              Comment

                              • stealthflanker
                                Rank 5 Registered User
                                • Sep 2015
                                • 1027

                                #75
                                Quick Update. Replacing the wavelength with Frequencies. User can now input frequency instead of wavelength. As why i picked MHz that's because it seems to be more convenient than GHz or KHz as well, from my experience, commonly people using radio use MHz and GHz is more often for Satellite communication or WIFI.

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                                Comment

                                • garryA
                                  Rank 5 Registered User
                                  • Dec 2015
                                  • 1120

                                  #76
                                  The problem is of course i haven't able yet to find a good "fudge factor" to take account of such uncertainties. Lowering the dB value based on the XST image might work but will it be applicable to any other object ?
                                  How about 2 different "fudge factor", one for simple angular shapes , one for stealth aircraft/ships ?

                                  Comment

                                  • stealthflanker
                                    Rank 5 Registered User
                                    • Sep 2015
                                    • 1027

                                    #77
                                    The simple shape would easily follows the wavelength dependency.Complex geometry Aircraft.. that could be a long way.

                                    My paper search so far however was not lucky. My idea is to try actually make various shapes and run it through computer modeling then attempt to relate it to the natural wavelength dependence. However I'm limited to the code that available to me. POFACETS alone might not be enough.

                                    Comment

                                    • stealthflanker
                                      Rank 5 Registered User
                                      • Sep 2015
                                      • 1027

                                      #78
                                      Latest Update :
                                      http://www.mediafire.com/file/s8ea52...able.xlsx/file


                                      In this update. I am again addressing the concern regarding the RCS, taking account of what apparently rarely discussed in typical forum board, namely Path Propagation Factor or "F" or "F^4". In any real world radar, the emitted and returned signal will inevitably bounce multiple times, and not only on target but also the nearby surroundings (land, sea etc). This inevitably creates interference. Be it destructive or constructive which will weaken or strengthen the signal. This phenomenon for ground based radars and perhaps Airborne one creates the well known lobing pattern in the coverage. In terms of RCS it will also affect the observable RCS, yielding what called as "Effective RCS". The effective RCS is the "free space" RCS multiplied with the path propagation factor. This value of RCS is the one a radar operator see. For academic/calculation purpose, the effective RCS alone could be enough for calculations of radar range. However applicability is limited to the type of radar and environmental condition surrounding it. Path propagation factor alone is product of surface electrical properties, target alititude, range and radiation pattern of the radar antenna. Thus without correcting for the propagation factor. Using RCS value obtained from one type of radar may not be applicable to the others.

                                      Calculations and modeling for F^4 factor is available, but relatively complex. Which i plan to incorporate later. At the time being the calculator im uploading now is using simplified approximation based on Flat earth assumption, perfect reflection surface and target located on first interference lobe. The value will arguably more applicable to radar that carried by naval vessel or aircrafts flying over sea than land.

                                      Depending on the frequency, antenna height and target altitude, the observed RCS can vary very wildly in range as depicted below.
                                      VHF Band


                                      X-band




                                      Notice the wild changes of RCS with just change of target altitude.

                                      The calculator features new tooltip "multipath" along with target and radar antenna height.



                                      When enabled. It will take account of the multipath based on the simple approximation. More complex model however will be available as soon as i managed to solve problem related to finding the proper way to incorporate antenna pattern into the calculator. As antenna pattern in elevation is required. User can also see the calculated path propagation factor and the Effective RCS.

                                      As for now one can see and "play around" with what's available and see how Effective/Observed RCS varies wildly as the path propagation factor changes. This basically allows the calculator to be used for Ground based radar. A word of caution however is that this assume the antenna is a "sector scan" type where the antenna is steered electronically. It cannot be used for rotating radar.
                                      Last edited by stealthflanker; 3rd September 2018, 11:04.

                                      Comment

                                      • halloweene
                                        Rank 5 Registered User
                                        • Jan 2012
                                        • 4351

                                        #79
                                        stealthflanker A former major engineer in AESA RBE2 program privately greeted your work...

                                        Comment

                                        • ActionJackson
                                          Rank 5 Registered User
                                          • Oct 2010
                                          • 289

                                          #80
                                          Are there any other variables being assumed in this calc? MDS, loss budgets, etc? Seems that if you want a calculator in any way accurate youd need to know a lot of classified stuff about the transmitter and receiver.

                                          Seems the list of variables on your spreadsheet wouldnt cover whats needed for single pulse or multiple pulse range calculation. Wheres the rest?

                                          Comment

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