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50 Ohm, 0.38% wavelength, Vertical Loop for the HF Bands

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WA7ARK, Jan 28, 2019.

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  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    Here is something I did for a friend that needed some help with modeling his proposed antenna. Comments requested.
     

    Attached Files:

    K7TRF likes this.
  2. KD6RF

    KD6RF XML Subscriber QRZ Page

    Interesting work. <thumbsup>

    You may want to get in touch with Jim WB5WPA - he has a lot of WSPR data on his mid-sized loop to my station and others. I believe he uses a different feed method, and the bands are 160 M and 80 M I believe, but could potentially provide useful confirmation of modeled efficiency.
     
    AA5CT likes this.
  3. SV1IYF

    SV1IYF Ham Member QRZ Page

    I modelled and actually built such a rectangular loop for 160m (H=~20m, W= ~9m, circumference =~58m, ~0.36 WL)
    Feed point at the middle of the low horizontal side.
    During the modelling phase I got a tiny bit better result by splitting the (fixed) capacitor to two units either side of the feed point.
    Absolute symmetry led to more current on the top horizontal part.
    During implementation I only tried the symmetrical configuration, consequently, I can't comment on any perceivable difference, if any.
    With motorized variable capacitors, as in the published study, things get much more complicated to the extend of not justifying it.
    On 80m, I couldn't TX, but on RX was having a better SNR compared to a trap 40/80m dipole at the same height as the upper part of the loop.
     
  4. AA5CT

    AA5CT Ham Member QRZ Page

    Our friend @KK5JY is into these kinds of loops too:) and they work well for him as well!
     
  5. AA5CT

    AA5CT Ham Member QRZ Page

    So good of you to have "run" through the numbers on paper.

    Now, here is how that sort of loop performs on 40 meters:
    https://www.qsl.net/wb5wpa/QWloop40m/

    Note the performance would improve with a larger gauge wire, or using copper in lieu of aluminum. Since this was a 'quicky', proof-of-concept test I lashed-up the implementation using the cheapest of available materials on hand ...

    Note: This work was done on the heels of work by Ben Edginton @G0CWT, and is in no way 'original' on my part.

    .
     

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