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Next Antenna… and Coax Decision

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  • Next Antenna… and Coax Decision

    Hey everyone,

    I'm currently using the Airnav antenna (the one from Amazon with the fixed 10m coax tail)
    https://smile.amazon.co.uk/AirNav-AD...qid=1619516958 &sr=8-7

    I'm in the market for upgrading it to one with a connector, so I can use decent cable.
    Any thoughts on my top three before purchasing?
    My main goal is picking up faint distant signals...

    1. Vinnant COL1090/7.5-P
    https://vinnant.sk/store/product/col109075-p

    2. Jetvision A3
    https://shop.jetvision.de/epages/648...Products/67020

    3. Pimorni
    https://shop.pimoroni.com/products/a...=GBP&utm_sourc e=google&utm_medium=cpc&utm_campaign=google+shoppi ng?utm_source=google&utm_medium=surfaces&utm_campa ign=shopping&gclid=Cj0KCQjwse-DBhC7ARIsAI8YcWIYzilXmfcqZjhCSJ5DKWpGhcJMtYxLuFfio Y_sSllEZ1WTk380RtsaAsumEALw_wcB

    I'm therefore also after a pre-made 10m (30ft) of the lowest loss coax at 1090Mhz.

  • #2
    Hi,

    as far as i can tell, the Jetvision A3 is a solid antenna, i got some improvements over my diy-spider-antenna (see coverage screens below), which are clearly related to the antenna. The graphs1090 images do not show improvements in signal strength. On the far left you can see the change from a ebay pcb antenna to the self-made spider, but to the right there is no change in signal strength or even a small drop after changing to the Jetvision A3 antenna. But since it's weatherproof - i think i keep it.

    Regards,
    Peter

    coverage_21-05-05.pngcoverage_21-05-10.pngdump1090-localhost-signal-30d.png
    Attached Files

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    • #3
      Hi Peter,

      Thanks for the info

      I've actually gone for a Jetvision A3 now, so I'm glad you agree!

      I also managed to source a 10m LMR400 coax cable with the correct connectors on, arriving this week.

      Just need to get it up on the chimney stack next, with a 3m pole, so I'm at maximum legal height

      Phil

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      • #4
        Originally posted by DoGGo View Post
        I also managed to source a 10m LMR400 coax cable with the correct connectors on, arriving this week.
        Cool, would be glad to hear about the improvements. Since i think i'm maxed out with antenna position and quality (balcony situation with other houses, so no free sight in some directions) i'm going to step up to a more capable Raspberry Pi (2 -> 3b+) and a direct connection of the stick to the Pi (i currently have to use a USB extension cable) and see what that brings.

        Peter

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        • #5
          I'll do a little post of my findings soon

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          • #6
            The gain of antennas is directional.

            As such a better antenna can mean the signal from aircraft on the horizon get stronger while those at an angle get weaker.
            Could also be that the adapter or coax from N to SMA has losses or something like that.

            Looking at message rate / range can be more useful.
            The gain seems a bit high to me anyhow...
            https://github.com/wiedehopf/adsb-sc...ptimizing-gain

            Comment


            • #7
              Hi wiedehopf

              in case you are referring to my posting/graphs, i'd be interested in suggestions - you can have a look at the complete graphs via http://34tznh9r5.dyn.cc/graphs1090/, i'm no expert at all, just curious to optimize my setup and find out what and how this all works - but for me it seemed to make more sense to focus on the rest of the hardware instead of improvements to the antenna. But maybe i got something wrong while installing the antenna, should it point somewhere or what did you mean with "directional"?

              I'm already using autogain (btw. i'm using much more from your scripts/guides, thanks for the work you put in and let us participate in you work ) so the gain setting should be set ok? Or is there improvement possible?

              Best regards,
              Peter

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              • #8
                You're probably just terrain or obstruction limited.

                https://github.com/wiedehopf/tar1090...-range-outline

                Nah gain is fine ... autogain will change a bit depending on how the traffic around you is (all high / near an approach etc)

                If you're not terrain / obstruction limited i'd say you need a filter or different SDR.

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                • #9
                  This is the view from the balcony, it covers the range vom approx. 60-240 or NE to SW... let's say, there are some minor obstructions I think i might even get some northerly signals from the reflection of the building right in front of me. But that's what i have to deal with and at least i don't have to care about the antenna being struck by lightning

                  IMG_2139.jpg

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