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Thread: Vertical antennas

  1. #1

    Vertical antennas

    I have a very narrow plot only 21feet x 100ft facing East. For the time being I am using ground planes for 20 n 40n. Recently I have added a "reflector" consisting of a 5% larger gp 2.97m behind the driven gp. Measured it at 7dB gain, 140deg lobe and 3 S units down from the back. Only drawback it is fixed and can't be turned. Anybody tried it?

  2. #2
    Administrator N8YX's Avatar
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    Why not put two (or more) equal length tuned radiators up and alter the pattern by feeding them in or out of phase?

    In a three-radiator-per-band system, your center radiator can be a trapped design. A 6BTV or similar would be ideal for this. Switching networks and phasing harnesses can be used to feed the outer radiators when directivity is desired.

    This approach also lends itself to multi-multi operations. Use a set of Dunestar or similar bandpass filters and a power combiner for feeding the array. Your 20 and 40M spots can control their arrays independently of one another, and the 10 and 75/80M spots will use the center radiator in an omnidirectional mode. (I'd avoid operating 15M unless you switch the 40M rig's bandpass filters accordingly and use it.)

    My ideal operating location is more square than rectangular - such as yours. A couple who is friends with a gal pal got a sweetheart deal on a piece of property that's 80x1400ft. Upon taking a look at the layout, I remarked that there's no way it would work for me. Doing this bit of engineering made me rethink that comment.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  3. #3
    Whacker Knot WTKX's Avatar
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    The late great W4RNL had a fantastic website that was acquired in a way that needed a subscription.





    http://www.antentop.org/w4rnl.001/radio.html

    Anyway, it is out there for all to view again.

    Small spaces suck, but do-able. Anyway, here is a cool design...

    http://www.antentop.org/w4rnl.001/triv.html

    And, the Moxon. http://www.antentop.org/w4rnl.001/moxpage.html

    I built one years ago that was made of wire, vertical, and I could rotate it.
    Most of the time we are punished if we go against the trend. Only at an inflection point are we rewarded. ~ George Soros



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