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Big Loops. What is the point of diminishing returns?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K0MBT, Nov 30, 2018.

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  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    A one-wavelength 160meter horizontal loop at 50ft agl is a cloud burner on 160m, better than a low dipole on 80m, but is the best antenna I have for 40m, where it also resonates. Good agreement between the actual antenna and modeling it. Not useful above 40m; too many deep nulls.

    I have enough land to lengthen it to two-wavelengths on 160m. Comparing the modeled patterns of the two-wl to the one-wl loop improves the pattern on 160m (more low angle radiation) but really screws up the 40m azimuth pattern. Since I am more interested in working 40m, I am going to leave it alone.

    The 80m pattern doesn't change much from 1 wl to 2 wl. Also doesn't matter hardly at all if it is fed in the corner or middle of a side.
     
  2. K6LPM

    K6LPM Ham Member QRZ Page

    Noteworthy Experiences, thanks for sharing. Interesting is the fact that the double 160 WL had little effect on 80 perhaps it is the height above ground or how low that is affecting this characteristic and may be a factor in determining the diminished return on lower bands. I would have hoped that the greater than full wavelength would have showed promise for nodes with lower angle of radiation on 80 when doubling the WL on 160.
    50 ft high is pretty much what I would assume the average upper limit of what is practical in most urban environments for the average hams home QTH,,,, Even that may be wishful for some hams?
    afterthought... DUH! 500+ ft of area to place the wire is very wishful for many hams ,,,, if someone has that much area to put wire over, then greater than 50ft high is much easier obtainable.
    fwiw I can barely squeeze 500ft of wire here and only can make 50ft I choose a little over a full wavelength on 80 opposed to a FWL 160 because the 250+ feet of wire generally loaded up better on all the bands for multiband coverage. Particularly on 17m
    My loop is in a sloper inverted delta configuration. YMMV
     
    Last edited: Apr 16, 2019

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