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Author Topic: 75 meter "bent" half square antenna questions  (Read 2433 times)
N2QLT
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Posts: 33




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« on: July 06, 2012, 11:22:38 AM »

Hello.

I just put up a 75 meter half square antenna on 45 foot supports (the tallest I have). I had to bend the legs in order to accommodate the vertical sections. I was surprised, because I had to trim the vertical sections all the way down to 58 ft in order to get the thing to resonate at 3800 khz. By my calculations, they should have been closer to 66 feet. The legs consist of about 45 feet of vertical, and 13 feet horizontal, bent 90 degrees and folded back parallel to the top section. The "bent" portion is up about 5 feet above the ground. Does that much trimming sound normal?

Also, do the bent portions have to be folded back in and parallel to the top section, or can they point in any convenient direction?

Any help would be appreciated.



73,
Scott
N2QLT
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WB6BYU
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Posts: 17476




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« Reply #1 on: July 06, 2012, 12:53:00 PM »

The capacitance to ground lowers the resonant frequency of the antenna, which is
why you had to shorten it.

The ends can be bent in any direction. 
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K4SAV
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Posts: 2437




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« Reply #2 on: July 06, 2012, 02:58:56 PM »

The legs consist of about 45 feet of vertical, and 13 feet horizontal, bent 90 degrees and folded back parallel to the top section. The "bent" portion is up about 5 feet above the ground.

If the vertical wire is 45 ft and the bottom of it is 5 ft above ground, how did you do that with a 45 ft support?
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N2QLT
Member

Posts: 33




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« Reply #3 on: July 06, 2012, 04:17:25 PM »

Actually the trees are about 55 ft. I am able to get 45 feet of wire vertical while leaving 5 ft above the soil. The antenna hangs a little, as it is not banjo string tight.
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