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Thread: best antenna

  1. #2541
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    Another Wire Collinear on internet.
    The Million dollar question: Has any one COMPARED it with an antenna of known performance like 1/4 wavelength groundplane (Spider/Cantenna)?

    Is any of this forum's members ready to make this one (or the other 2 drawings posted in my previous post) and run a comparison test with a 1/4 wavelength groundplane antenna?

    Without comparison (like I have done with my wire collinear), claims of high gain are NOT acceptable, even if supported by simulation results.

    http://www.qsl.net/py4zbz/adsb.htm

    The site is in Portuguese language. A translation in English gives following details:

    "The upright elements 3 is 136, 205 and 183 mm in length respectively (from the connector). The 4 ground plane of the rods is 69 mm each. As this antenna has 75 ohms radiation resistance, I used a RGC-06 cable (60%) with 12 meters to the E4000, whose input impedance is also 75 ohms.
    Detail of one of the two coils 1/4 wave perimeter (69 mm) and 22 mm in diameter:"



    ANT1.jpg ant3.jpg sa3.gif sa2.gifsa4.gif

  2. #2542
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    I think the reason you are finding better results with a 1/4 wave is that the radiation pattern is raised in comparison to a colinear or any other loaded antennae.

    Building a "high gain" antenna means you are compromising SOMETHING !
    In amateur radio we build antennae that offer a low angle of radiation because we know the other station is on the ground ;-)
    You never get anything for nothing in this game, and by making antennae bigger than 1/4 you are gaining distance at the expense of height - and therefore loosing range overhead.

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    Last edited by abcd567; 2016-07-27 at 21:46.

  5. #2545
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    that last one i have actually built and it was OK, think i still have the results somewhere ( have formatted once or twice since then)

    @abcd567 I'm glad they are different lengths i thought my eyes were playing tricks.
    @ccz i have often thought about doing it like but wandered how to support the elements let me know how it works out with printed spacers
    Last edited by SpaxmoidJAm; 2016-07-27 at 21:26.
    T-EGLF8

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    Last edited by abcd567; 2016-07-27 at 21:52.

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  8. #2548
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    Below is a photo of some of the collinear whips I have tried. Many others are not in this photo as those ended up in trash can.

    All these whips were optimized by simulation, which showed Gain much greater than, and SWR much less than the 1/4 wavelength groundplane (Cantenna).

    However when I replaced the 1/4 whip of Cantenna by these whips, the performance dropped drastically.

    All the antenna designs I have come across on web have same approach. After making their antenna, they connect it to DBV-T, and aicrafts popup on their screen. They then claim it as very good antenna. No one has ever presented a quantitative comparison with a benchmark antenna. Their attitude is like a person who runs alone in a race, and at the end of race declares himself the winner.

    Note:
    The button like thing on left side of the top-most whip is an adjustable capacitor (trimmer/padder) 2 to 7 pf.
    I inserted it to nullify the inductive component of antenna impedance to improve SWR.


  9. #2549
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    Quote Originally Posted by abcd567 View Post
    Another Wire Collinear on internet.
    The Million dollar question: Has any one COMPARED it with an antenna of known performance like 1/4 wavelength groundplane (Spider/Cantenna)?

    Is any of this forum's members ready to make this one (or the other 2 drawings posted in my previous post) and run a comparison test with a 1/4 wavelength groundplane antenna?
    I have tried them before but I can't say comparisons were very thorough. My results were worse for these wire collinears but only based on momentarily observations.
    I have now a known good cantenna with a few days range plot that I can compare it to.

    Just built the one from this post and will put it up in a few minutes. Will make range plot and report it after 24-48h.
    Antenna details were respected exactly, like you wrote them. Wire used is same as cantenna to eliminate this difference too.


    Quote Originally Posted by abcd567 View Post
    The site is in Portuguese language. A translation in English gives following details:

    "The upright elements 3 is 136, 205 and 183 mm in length respectively (from the connector). The 4 ground plane of the rods is 69 mm each. As this antenna has 75 ohms radiation resistance, I used a RGC-06 cable (60%) with 12 meters to the E4000, whose input impedance is also 75 ohms.
    Detail of one of the two coils 1/4 wave perimeter (69 mm) and 22 mm in diameter:"



    ANT1.jpg ant3.jpg sa3.gif sa2.gifsa4.gif
    Please follow link in original post is interested, I still can post links.

  10. #2550
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    I stopped the experiment. I picked up almost nothing. I can't believe that I am so bad at bending a simple wire.
    Totally can't understand the results I'm getting.
    Even the simple pushed-in coco I did performed like the cantenna. I am at a loss here.


    Attached are plots for the following:

    - wire collinear 2h, run for the last 2 hours
    - reference cantenna (48h plot)
    - cantenna 2min, run for 2 minutes after changing back from wire collinear

    Edit: circles are 50nm each
    Attached Images Attached Images

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