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QUICK SPIDER - No Soldering, No Connector

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  • abcd567
    replied
    Originally posted by apeiron69 View Post
    It doesn't matter the cable RG6 is 75 ohm?

    No, it does not make any difference as the DVB-T dongle has input impedance of 75 ohms. The DVB-T is designed for TV reception, and the TV system uses 75 ohm.

    Even if the dongle was 50 ohms, in receiving situation like we are, the mismatch between 50 and 75 ohms does not cause an appreciable loss in performance (the SWR for 50 to 75 transition is 1.5, and mismatch loss is only 0.177 dB). As in receiving scenario, the power levels are in milli or even micro watts, which are easily compensated by front end circuits of the dongle.

    For transmitting equipment the 50 to 75 ohm mismatch should be avoided to reduce reflected power, as the power levels involved are in watts or tens of watts or even hundreds of watts.
    Last edited by abcd567; 2020-06-15, 14:48.

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  • apeiron69
    replied
    It doesn't matter the cable RG6 is 75 ohm?

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  • Conan_89
    replied
    My first try to biuld a anntenn.
    And the result is:
    The included mini telescopic antenna has better reception than my built -.-
    Attached Files

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  • 9944990
    replied
    I make one of these which I use with my Jetvision USB dongle connected to my Pi 3 B+. I get three times more position reports and hits and slightly more plane counts and range than the stock antenna.
    However I am not able to achieve this when i a new one for my second feeder, I tried with 5 new spider.

    I use the same cable, cable length even place in the same position as the first one and connect it to my first feeder results are not good at all, I get around 20% of what I received with my first antenna.

    What am I missing? Where should I look to find the problem?

    Leave a comment:


  • abcd567
    replied
    Originally posted by Conan_89 View Post
    @abcd567
    when i bulid this anntenn.
    Do I need a special cable to connect to my nooelec nesdr Mini 2+?
    Yes. The nooelec nesdr Mini 2+ site says:
    "The connector type on the antenna and USB board is MCX--male MCX on the antenna, female MCX on the SDR"

    NooElec NESDR Mini 2+.jpg


    You will need a pigtail to connect the "nooelec nesdr Mini 2+" (MCX female socket) to RG6 cable of Spider (F-male connector)

    Pigtail F-female to MCX-male Rightangle.jpg OR Pigtail F-female to MCX-male Straight.jpg


    SEARCH RESULTS ON EBAY GERMANY
    https://www.ebay.de/sch/i.html?_from...Pigtail&_sop=2

    SEARCH RESULTS ON AMAZON GERMANY
    https://www.amazon.de/s/ref=nb_sb_no...MCX+Male+RG316
    Last edited by abcd567; 2018-08-01, 16:48.

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  • Conan_89
    replied
    @abcd567
    when i bulid this anntenn.
    Do I need a special cable to connect to my nooelec nesdr Mini 2+?
    Currently I have a reception radius of about 50nm(what is nm suitable?), I would like to expand it, possibly I get the Stuttgart airport in.

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  • Coxy
    replied
    Still the best Ant i have made and the best range including against bought ones...

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  • abcd567
    replied
    .
    .

    GROUNDPLANE ANTENNA MADE OF COAX ONLY - Without SO239 or N-Conector

    .

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  • goku1976
    replied
    Following abcd567 post I did my own spider antenna. Here it is.
    I used Thermal tail to isolate metal parts from the rain and also I have lately raised it to get a better performance.

    Leave a comment:


  • abcd567
    replied
    mibock
    I never tried glueing radials to Flightaware anena, so cannot tell you anything. You may try it.


    Following may help

    (1) Reducing gain setting of dongle. Try different values say 45 , 40, 35, 30,25,and at each gain setting run your pi for some period and watch. Since nearby plane's signal is strong, their signals may not be processd due to overload. Reducing gain may result in the nearby planesalso start showing.

    (2) Adding a filter.
    Last edited by abcd567; 2018-07-18, 19:36.

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  • mibock
    replied
    Thank you for your answers, abcd567. :-) You seem to be the Mr. Antenna from what I read.

    So I come to my next question:

    what happens if I glue the 45-degree-wires to the outside of my flightaware-antenna? Would I have better reception of near planes?

    It would have no contact like your solution to the inner wire because of outer isolation. :-)

    And a question I posted in my first post in this forum later, where you helped me with installation.

    The landing planes which I do not see are in an angle of about 25 to 35 degress to my position, 500 metres away. I understand if they would fly high above me that the antenna can not get them, but nearly horizontal I do not understand.
    So maybe an additional filter you wrote in the other post from today may help better. I live in Hamburg next to one of the fly-in/out-spots.

    Leave a comment:


  • abcd567
    replied
    Originally posted by mibock View Post
    Do I understand it correctly that

    - the outer wires have no contact to the inner wire?
    Correct.
    The outer wires are connected only to the braid & shield of coax. These have no connection to central wire of coax.

    - that this kind of antenna helps against doughnut-effect with very near planes during landing and starting?
    No, it does not eliminate doughnut effect, but nearby planes are picked somewhat better than a high gain antenna.


    - that the blue plastic-thing helps reflect waves from nearby planes?
    Totally wrong. The blue plastic thing is a support, and does NOT contribute or affect antenna performance


    - does the blue plastic-thing helps with nearby planes if I put it under the 68cm flight-aware-antenna I have bought?
    No, it wont help. It has no effect on antenna performance. It is just a support.
    Last edited by abcd567; 2018-07-18, 15:33.

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  • mibock
    replied
    Do I understand it correctly that

    - the outer wires have no contact to the inner wire?
    - that this kind of antenna helps against doughnut-effect with very near planes during landing and starting?
    - that the blue plastic-thing helps reflect waves from nearby planes?
    - does the blue plastic-thing helps with nearby planes if I put it under the 68cm flight-aware-antenna I have bought?

    Leave a comment:


  • perseus68
    replied
    Well, I wanted to give it a try as my first ads-b antenna and this tiny GP gave me 500Km (i.e. 270nm) of coverage at the first attempt !!
    I have to admit that my balcony is at 330m above sea level and I only have the ocean in front of me and this helps a lot
    Nevertheless I have no coverage toward the West.
    Im really happy so far but Im already building a J-pole for more coverage before start feeding FR24 with my brand new Orange Pi PC Plus.

    Btw as you can see I kept the cable to the minimum :-)

    IMG_20170426_153009.jpg

    IMG_20170426_194854.jpg

    Thanks abcd567 ;-)

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  • joni1101
    replied
    Very interesting. Amazing how these small changes in geometry affect performance. Best bet is 45 seems like?

    Sent from my Pixel using Tapatalk

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