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Passive sensor & L-band radar of USA ?

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  • blackadam
    Rank 5 Registered User
    • May 2013
    • 229

    Passive sensor & L-band radar of USA ?

    Russia: PAK FA and MiG-31 have L-band radar as NIIP (Tikhomirov AESA) & Zaslon-AM
    Israel has EL/M-2080 L-band radar
    Ukraine has Kolchuga passive sensor

    L-band radar can detect stealth aircraft such as F-22 or F-35, L-band radar can be switched on constantly and not easily detectable (similar AESA radar, but L-band radar does not change the frequency as AESA), because when installed onboard the aircraft's nose, made from materials compousite not reflect radar waves from radar such as the APG-77 X-band (3cm) used track MiG-31 or T-50 (note: head-on), in addition to the sensor surface as Kolchuga or AESA radar EL/M-2080 ground-base can effectively resist attacks from the EA-18G (electronic warfare) or ARM missiles like the AGM-88 HARM.

    AESA radar can change frequencies continuously & AGM-88 will be elusive, with passive sensor AGM-88 can't be detected because it is receiving signals from the noise of the engine as well as radar (The stealth aircraft while operating the equipment required to open as radio contact with the command center, equipment altimetry, radar to find targets. passive sensor receive these signals to detect targets), so it does not emit as radar frequency to & AGM-88 can't find (Except for the use of guided bombs as the JDAM, TLAM, used Targeting pod).

    Finally What the USA got ?
    Last edited by blackadam; 4th September 2013, 14:42.
  • Goldust
    Senior Member
    • Jun 2012
    • 483

    #2
    Radio wave is the same no matter what band, so why would L band be better for detecting so called stealth?

    Comment

    • MSphere
      Senior Member
      • Feb 2010
      • 8983

      #3
      Originally posted by Goldust View Post
      Radio wave is the same no matter what band, so why would L band be better for detecting so called stealth?
      Ever heard about something called wavelength?

      Comment

      • Goldust
        Senior Member
        • Jun 2012
        • 483

        #4
        Originally posted by MSphere View Post
        Ever heard about something called wavelength?
        Why would wavelength affect detecting stealth?

        Comment

        • Goldust
          Senior Member
          • Jun 2012
          • 483

          #5
          Speaking of passive sensors, every object exerts a gravitational force. Say if you have an F-22 at 100 km away, it would exert a large gravitational force given its large mass of 43,340 pounds of empty weight. This would enable it to be detected and tracked by some sort of passive gravity detection sensor.

          Comment

          • MSphere
            Senior Member
            • Feb 2010
            • 8983

            #6
            Originally posted by Goldust View Post
            Why would wavelength affect detecting stealth?
            Because wavelength in certain band directly relates to the size of the illuminated object and that affects its RCS.
            If you take a small metal ball and drill a tiny hole in it, then the hole will have next to zero effect on the RCS when illuminated by a meter long wave.
            But the same role can have great impact on the RCS of the ball when illuminated by radar waves with very high frequency (short wavelength).
            Logically - you optimize shape for specific frequencies only (the ones you most likely encounter on battlefield, of course)

            Comment

            • MSphere
              Senior Member
              • Feb 2010
              • 8983

              #7
              Originally posted by Goldust View Post
              Speaking of passive sensors, every object exerts a gravitational force. Say if you have an F-22 at 100 km away, it would exert a large gravitational force given its large mass of 43,340 pounds of empty weight. This would enable it to be detected and tracked by some sort of passive gravity detection sensor.
              And how exactly does such sensor work?

              Comment

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

                #8
                Northrop First flew a L Band AESA nearly a decade ago

                http://www.northropgrumman.com/Capab...s/default.aspx

                The most prominent of the many antenna and optical apertures is the MESA “top hat” AESA antenna subsystem shared between the L-band radar and its integrated IFF system.
                http://www.ausairpower.net/APA-Wedgetail-Antennas.html

                The 737 AEW&C aircraft generates 360 kilowatts of electrical power to operate the MESA radar. In addition, the aircraft can carry radar antennas that are very large, approximately 6 x 18 feet for the side-looking antennas and 5 x 25 feet for the forward- and aft- looking antennas. This antenna size, plus the radar power, enable the AEW&C aircraft to survey great distances. The MESA radar antennas are housed in a dorsal structure mounted on top of the fuselage. There are two back-to-back sideward looking arrays and a third antenna—called the “top hat” and positioned high in the dorsal in—that looks front and back. These full coverage arrays, along with their component electronically steered T/R modules, enable MESA system operators to focus radar time and energy on the areas more likely to include hostile targets while simultaneously monitoring low threat areas with less radar energy.

                Another major AESA surveillance system being designed and developed by Northrop Grumman is the next-generation radar for the Global Hawk and the E-10 aircraft. The design utilizes technology advances from development work on tactical aircraft for these surveillance platforms.

                The great range and exceptional agility that make AESA systems so well suited to the early warning mission also figure importantly in their effectiveness as fire control radars for fighter aircraft. An additional strength enhances fighter operations: the ability to achieve high-resolution imagery for air-to-ground targeting. AESA fighter radars, because they use X-band frequencies and synthetic aperture processing, are capable of such “targeting-quality” resolution. This is not the case for the AEW&C MESA radar: it uses lower, L-band frequencies, settling for lower resolution in order to achieve long range detection with less disruption from bad weather.
                http://www.northropgrumman.com/Capab...eview_aesa.pdf

                Passive targetting and detection (F-22 & F-35)

                F-22

                The AN/ALR-94 is a passive receiver system capable of detecting the radar signals in the environment. Composed of more than 30 antennae smoothly blended into the wings and fuselage, it is described by the former head of the F-22 program at Lockheed Martin Tom Burbage as "the most technically complex piece of equipment on the aircraft." With greater range (250+ nmi) than the radar, it enables the F-22 to limit its own radar emission which might otherwise compromise its stealth. As the target approaches, AN/ALR-94 can cue the AN/APG-77 radar to keep track of its motion with a narrow beam, which can be as focused as 2 by 2 in azimuth and elevation.
                The AN/APG-77 AESA radar, designed for air-superiority and strike operations, features a low-observable, active-aperture, electronically-scanned array that can track multiple targets in all kinds of weather.



                http://piaairslines.blogspot.com/200...er-system.html

                The ALR-94, in addition to being described as the most sophisticated kit aboard the F-22, is also the most protected (classified) as far as sub systems are concerned...

                F-35

                F-35 Sensor Suite

                http://www.aviationtoday.com/av/issu...l#.UidNtGSsgXw
                http://www.aviationtoday.com/av/mili...l#.UidQnGSsgXw
                Attached Files
                Last edited by bring_it_on; 4th September 2013, 16:04.
                Old radar types never die; they just phased array

                Comment

                • Goldust
                  Senior Member
                  • Jun 2012
                  • 483

                  #9
                  An F-15 weighs 28,000 pounds empty. An F-22 weighs 43,340 pounds empty. An F-22 thus has a much larger gravitational signature than an F-15. Anyone know which of the two has a larger infrared signature at cruising speed?
                  Last edited by Goldust; 4th September 2013, 15:35.

                  Comment

                  • maurobaggio
                    Rank 5 Registered User
                    • Jul 2008
                    • 521

                    #10
                    Originally posted by Goldust View Post
                    Radio wave is the same no matter what band, so why would L band be better for detecting so called stealth?
                    Although equal are also different ...
                    If you want to have fun on this follows below some links on this topic:

                    http://www.ausairpower.net/index.html

                    http://www.ausairpower.net/APA-Rus-Low-Band-Radars.html

                    http://www.ausairpower.net/APA-2011-03.html

                    http://www.ausairpower.net/APA-2009-06.html

                    Comment

                    • Goldust
                      Senior Member
                      • Jun 2012
                      • 483

                      #11
                      It says here that radar absorbing paint can turn radio waves partially into heat. This can be done only by reducing the energy of the reflected radio waves, that is to say, by changing the wave length. Suppose a radar sends out radio waves at a certain wavelength, and the returning radio waves have their wavelengths altered, wouldn't this be a tell tail sign that radar absorbing paint was encountered and the stealthy aircraft detected?

                      http://en.wikipedia.org/wiki/Radar-absorbent_material

                      Comment

                      • TooCool_12f
                        Rank 5 Registered User
                        • Dec 2009
                        • 3319

                        #12
                        er, no, the energy depletion will reduce the intensity of the signal (the whole purpose of the RAM paint) but won't change the wavelength as such

                        Comment

                        • halloweene
                          Rank 5 Registered User
                          • Jan 2012
                          • 4343

                          #13
                          Bring it, conformal antennas were dismissed from F22. Years ago and was never produced.
                          Bah nvm, this wole thread is onsense, every countries are working on passive multistatic radars, some prototypes are funded using UHF, VHF, MF and Numerical TV frequences.

                          Comment

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

                            #14
                            Bring it, conformal antennas were dismissed from F22. Years ago and was never produced.
                            Those were side array AESA that worked along side the Apg-77 and increased its FOV. The original LMA proposal called for 3 radars in the Nose (Similar to T-50) and side arrays. Side arrays were deffered, and may perhaps re-appear during MLU. The Antennas are a part of the F-22 Passive suite, and are very much on the fighter.
                            Old radar types never die; they just phased array

                            Comment

                            • halloweene
                              Rank 5 Registered User
                              • Jan 2012
                              • 4343

                              #15
                              Ah ok confused. btw, side (conformal) arrays on the way also at Thals.

                              Comment

                              • Goldust
                                Senior Member
                                • Jun 2012
                                • 483

                                #16
                                Originally posted by TooCool_12f View Post
                                er, no, the energy depletion will reduce the intensity of the signal (the whole purpose of the RAM paint) but won't change the wavelength as such
                                Radio waves travel at the speed of light. What does it mean by reduced energy?

                                Comment

                                • halloweene
                                  Rank 5 Registered User
                                  • Jan 2012
                                  • 4343

                                  #17
                                  When you put your hand on a fire, you will absorb some of its energy (and eventually get burnt)

                                  Comment

                                  • Goldust
                                    Senior Member
                                    • Jun 2012
                                    • 483

                                    #18
                                    A radar should not care about the energy of the reflected waves. It only needs waves to be reflected back to it to register a detection of a distant object. Isn't this correct?

                                    Comment

                                    • MancFrank
                                      Beer, fags and skittles
                                      • Aug 2008
                                      • 62

                                      #19
                                      Originally posted by Goldust View Post
                                      Speaking of passive sensors, every object exerts a gravitational force. Say if you have an F-22 at 100 km away, it would exert a large gravitational force given its large mass of 43,340 pounds of empty weight. This would enable it to be detected and tracked by some sort of passive gravity detection sensor.
                                      No. You might, in theory at least, be able to detect a peturbation within the Earths gravitational field rather than the gravitational influence of the object itself. But not without a detector the size of a small town and months to process the data. If you know otherwise, I'm sure the world's leading physicists will be beating a path to your door shortly!

                                      Regards,

                                      Frank

                                      Comment

                                      • halloweene
                                        Rank 5 Registered User
                                        • Jan 2012
                                        • 4343

                                        #20
                                        if the radar is (i) sensitive enough and (ii) recognize waveform

                                        Comment

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