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Comparing ADS-B 1090MHZ Antennas, 2.0dBi antenna and 12.0dBi

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  • #16
    This is the spectrum directly at the antenna,

    1075-1125.jpg


    this is the spectrum after 10 meters of cable

    other side of cable.JPEG

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    This gallery has 2 photos.

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    • #17
      A 12dbi antenna for 1090 MHz must be around 1.8 meters long. There are no shortcuts to the relation of gain vs physical size. So unless it is roughly that size, it is fake. Has nothing to do with quality, PCB material etc, there simply isn't enough elements. And, making a vertical 360 deg antenna with more than 9-10 dBi gain is extremely difficult to get right.

      Here is a real 9dBi antenna, 144 cm long.

      Specs Gain:  9 dBi SWR:  1.5:1 or Less Pattern:  Omni-directional Wavelength:  Multiple 1/2 Tuned:  1090 MHz Band:  Mode-S / ADS-B Connector:  N Female Cable:  RG8X Cable Length:  24 Inches Height:  57" Width:  1 1/4" Weight: 2 lb 2 oz Wind Area:  0.50 Sq Feet     Features Ready Made:  There's no assembly necessary, or
      F-ESDF1, F-ESGG1, F-ESGP1, F-ESNK1, F-ESNV2, F-ESNV3 F-ESSL4, F-ESNZ7, F-LFMN3
      T-ESNL1, T-ESNL2, T-ESGR15
      P-ESIA, P-ESIB, P-ESGF, P-ESSN, P-EFMA
      mrmac (a) fastest.cc

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      • #18
        Originally posted by MrMac View Post
        A 12dbi antenna for 1090 MHz must be around 1.8 meters long. There are no shortcuts to the relation of gain vs physical size. So unless it is roughly that size, it is fake. Has nothing to do with quality, PCB material etc, there simply isn't enough elements. And, making a vertical 360 deg antenna with more than 9-10 dBi gain is extremely difficult to get right.

        Here is a real 9dBi antenna, 144 cm long.

        https://dpdproductions.com/products/...r-base-antenna
        full wave at 1090mhz is 27.5cm so that antenna is probably 5 antennas stacked. I made one of those some years ago after seeing it on hack5 youtube but it didnt perform very well.

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        • #19
          Originally posted by tqf View Post

          full wave at 1090mhz is 27.5cm so that antenna is probably 5 antennas stacked. I made one of those some years ago after seeing it on hack5 youtube but it didnt perform very well.
          Like I said, building a high-gain vertical is EXTREMELY difficult without proper tools and measuring equipment, and not only SWR. I used to work for one of the world's largest antenna manufacturers, and even for us it was very hard to get the pattern correct. And we had a 2 million USD compact range all to ourselves...

          There are a lot of desciptions out there like "balarad" for antennas with a lot of elements, but any self-build of more than 3-4 elemenst is normally pointless.
          F-ESDF1, F-ESGG1, F-ESGP1, F-ESNK1, F-ESNV2, F-ESNV3 F-ESSL4, F-ESNZ7, F-LFMN3
          T-ESNL1, T-ESNL2, T-ESGR15
          P-ESIA, P-ESIB, P-ESGF, P-ESSN, P-EFMA
          mrmac (a) fastest.cc

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