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  • moved temp. antenna

    Good morning all. My setup here in Mathews, Va. since putting my Pi3+ with FR24 on the air has been portable and probably will be until next year when I hope to be moved in to my new home. For the time being my antenna is basic and placed wherever I can put it. Since starting I've had the antenna stuck to the east facing window in the one story office at the marina where I work. It is a vertical dipole with the suction cup base that came with the RTL-SDR. This morning I decided to try placing the antenna outside and up higher. I have a 20ft collapsible fishing pole in my car that I use for supporting my wire antennas when I operate a portable low-power (qrp) ham radio hf transceiver. I decide to use the fishing pole for supporting the antenna for my FL24 setup. I didn't have enough coax to go the whole 20ft so it's about 12ft high. I'm using batteries to run the pi. WOW! What a difference location makes!! Before changing locations, the data read:
    AIRCRAFT SEEN: 213 POSITIONS REPORTED: 321 MAXIMUM DISTANCE: 13NM HITS REPORTED: 2472

    It took about 20 minutes to relocate everything and after booting up I came back over to the office and made a cup of coffee. Then I sat down and looked at the data:
    AIRCRAFT SEEN: 254 POSITIONS REPORTED: 1290 MAXIMUM DISTANCE: 73NM HITS REPORTED: 5095

    And now, thirty minutes later I see:
    AIRCRAFT SEEN: 309 POSITIONS REPORTED: 3474 MAXIMUM DISTANCE: 84NM HITS REPORTED: 11290

    Anyway, just wanted to share this with the group.

    flightstuff.jpg setup in office at work
    fr24_portable.jpg setup outside using portable fishing pole for a mast
    Last edited by luckylindy; 2018-12-18, 14:17.
    de WA4CHQ/qrp 99% cw since 1972. Linux using SLACKWARE since 2000

  • #2
    The transmission of ASDB signal is on microwave frequency, hence it is a line-of-sight situation: the receiving antenna should be able to "see" the transmitting antenna on the plane.

    Due to curvature of earth, the line of sight formed between receiving antenna and the farthest plane it can see is a horizontal line.

    Hence an antenna can see the farthest if it can "see" the horizon. If you stand next to antenna, and you can see horizon, then your antenna also sees horizon.

    To achieve this, the antenna should be slightly above the height of surroundin tall objects like houses, buildings, and tall trees.

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    Last edited by abcd567; 2018-12-19, 02:43.

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    • #3
      Thanks for the info. Yes, I understand the line of sight situation at these frequencies, but I didn't expect to see the results I got with an imperfect antenna and having only raised it up by a maybe six feet. Waiting on parts to build the "Cantenna". I'm looking forward to comparing the results!

      (lived in Thornhill from '64-67....boy, has Arnold Ave. changed!)
      Last edited by luckylindy; 2018-12-19, 12:31.
      de WA4CHQ/qrp 99% cw since 1972. Linux using SLACKWARE since 2000

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