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Thread: A Cycloid Dipole CP antenna to shrink the size of tx antennas for lower frequencies

  1. #1
    Navigator Kondor-FPV's Avatar
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    A Cycloid Dipole CP antenna to shrink the size of tx antennas for lower frequencies

    Just to bring more to the table, (and I kick myself in the butt for doing so without having the time).

    This is the antenna I am working on, and it's very simple.

    It's RHCP and so far it has all but equaled the performance of the Pinwheel .

    The gain of the Cycloid Dipole is about 1.8 Db over an isotropic antenna ,while the pinwheel is 1.7dbi... so gains are about equal.

    The first flight test has been made and I see no difference so far, even if the Cycloid is just coming in at 1.5:1 SWR.

    I am sure I can tweak the SWR a bit more, but need to make sure that the radiation properties stay the same.

    The video stays solid with the plane rolling all over the place at distances up to 4km with a Pinwheel on the rx and a Cycloid on the plane.

    I am very excited, but still need to work on the antenna to make it better, and I also need to test with a cycloid both on the plane and on the ground station before calling it a winner.

    Here is a size comparison with its direct opponent the Pinwheel, of course both are tuned to the same frequency of 2430mhz.
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    Last edited by Kondor-FPV; 2nd June 2012 at 04:33 PM.
    www.fpvlr.com - Home of your favourite Custom FPV antennas.

  2. #2
    Navigator Kondor-FPV's Avatar
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    I won't post this on rcgroups... that's a Noobs' nest nowadays... Sigh!
    www.fpvlr.com - Home of your favourite Custom FPV antennas.

  3. #3
    The World as We See It Twawsi's Avatar
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    ^ +1

    Amen, you're preaching to the choir brother! Best of luck Kondor

  4. #4
    His Royal Sassiness ssassen's Avatar
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    Ah yes, I have a few of those, getting them tuned on low frequencies was easy, but on 2.4GHz and 5.8GHz it becomes very, very critical. Anything metal or conducting (CF for example) near the antenna would offset it and shift the resonance, running wiring near it that carries ground on the same circuit would ruin the performance. However out on a wingtip it fared well, so perhaps I should revisit?
    Velvety smooth drone pilot for hire

  5. #5
    Navigator Kondor-FPV's Avatar
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    yes, but there is even a better iteration of this antenna with 3-4dbi gain... but that's for later.

    I think the antenna has potential. If you want an advice, use 2mm solid copper for better stability and bandwidth, I haven't tried thicker but 3mm brass tubing would probably be even better.
    www.fpvlr.com - Home of your favourite Custom FPV antennas.

  6. #6
    GO HAWKS Hucker's Avatar
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    Quote Originally Posted by Kondor-FPV View Post
    I won't post this on rcgroups... that's a Noobs' nest nowadays... Sigh!
    RCG is a gateway forum to FPVLabs

  7. #7
    Banana Drone Flying Monkey's Avatar
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    Looks neat! Can you provide a build log... more pictures... and dimensions for different frequencies? For now I'd like to try this on 910mhz. Does the little wire go to the ground or signal? Looks like it connects to the thicker wire, how far up?

    PS: Building my first Viravent right now!
    "You can't take the sky from me"

  8. #8
    KC8UD GLEvideo's Avatar
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    This looks very similar to a design we used to install for FM radio stations which allowed for both horizontal and vertical polorization. I don't remember the term circular polorization being used with them back then but they truly could be. It's a proven design. Good luck with it.
    Airplanes LIKE to fly : Helicopters WANT to kill you.

  9. #9
    Shedding light over FPV HugeOne's Avatar
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    PS: Building my first Viravent right now!
    Virevent (french for pinwheel)

    -Hugo

  10. #10
    Banana Drone Flying Monkey's Avatar
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    Quote Originally Posted by HugeOne View Post
    Virevent (french for pinwheel)

    -Hugo
    Oops! Wait, I thought the pinwheel was OMM's name for the skew planar?
    "You can't take the sky from me"

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