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Thread: Help with my antenna!!

  1. #1
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    Help with my antenna!!

    Hello, i need help with my antenna that from any reason it doesnt work when i connect it to the feeder cable (cable is not damaged or something) when i connect the antenna directly to my laptop on the rooftop i get about 9-10 planes (within 100-150 nm), but once i connect it to the feeder cable to my apartment from the rooftop (its like 5 mts), i dont get any signal plus i get this on the SISEX program in rtl1090:

    Attachment 4970

    This is my antenna and this is my view:

    01e09a061f4b4da425c3f070a3274b7034890457e4.jpg01fe74817eb91c1279fbc2a17e168cb45ab7641332.jpg012dba1b28c2772af3afe7480e49ed1d80a0c25104.jpg014bb795ede2f03189da21cbb99175bebfd562e648.jpg0155fad83e32ca48cf1d92073a96cb5f7c3a7f8d5a.jpg

    PS: I tried a 16 elements collinear-coaxial antenna with no success, aparently this little antenna have more power than the Co-Co antenna.

    Please help

  2. #2
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    The moment you add those 3 connectors, your signal is all but lost before it gets to the cable.

    For every connector you can expect 1-3dB loss. And I see there you have N, to BNC, to F. And no doubt only RG6 cable? Which means what little signal you had, is now full of noise or not definable.

  3. #3
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    Quote Originally Posted by Oblivian View Post
    The moment you add those 3 connectors, your signal is all but lost before it gets to the cable.

    For every connector you can expect 1-3dB loss. And I see there you have N, to BNC, to F. And no doubt only RG6 cable? Which means what little signal you had, is now full of noise or not definable.
    oh... i see... so what do you recomend??

    Thanks

  4. #4
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    Quote Originally Posted by Adelgallego View Post
    oh... i see... so what do you recomend??

    Thanks
    I would suggest you replace the connector used for the antenna to fit the cable directly, or replace cable/connectors with some high frequency low loss ones.

    For 1090 Mhz it is recommended to use RG214 or LMR400 cable, with N-type connectors

  5. #5
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    With the whole assembly in place - go down to the receiver end and

    put a meter between the co-ax shield and core - to test it's not shorted.

    Then connect the antenna whip to the ground plane (using a short length of wire and some crocodile clips or something) - and repeat the test to ensure all the connections are low resistance.

    I did have my Bulgarian antenna (below) connected with a few adaptors (N to F, F on the downlead, then 75ohm TV to dongle adaptor) with 8m of RG6 and was getting 350-400km radius.

    ----
    if it's easy to pull the downlead out - try the antenna + downlead where you tried with the little antenna that came with the dongle - does it work there.

    Where some have had problems woth the external antenna, it's bee related to the location ... when on the roof the antenna having a nice clear view of a 900mhz cell tower 200m away - the signal from that forcing the dongle gain to be automatically turned down.
    Last edited by peterhr; 2014-10-30 at 07:49.

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