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Re: [TowerTalk] Choke on feed point of dipole

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Choke on feed point of dipole
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 12 Jan 2026 16:31:30 -0800
List-post: <mailto:towertalk@contesting.com>
On 1/12/2026 3:48 PM, Richard (Rick) Karlquist wrote:
the well established principle that elevating a vertical doesn't work very well in the first place, no matter what is done to feed it.

In a study of the height of vertically polarized antennas that I published in parallel to the one on horizontally polarized antennas, I showed that there CAN be benefit to modestly elevating quarter-wave HF vertical antennas. The study looked at typical roof heights for single family homes. The The benefits are on the order of a few dB -- reduced ground losses and lowering the angle of maximum field strength.

Making the antenna a half-wave improves the vertical pattern by raising the height of the current maxima, just as elevating quarter-wave vertical does. And the end-feed arrangement used for half-wave wires would likely work just as well (although we might not like the vertical pattern when operating on harmonics).

There's another reason my feed arrangement could be useful -- rigging from a single support, like tossing a rope over a tree limb. I like to show methods that give folks more options, depending on their real estate.

73, Jim K9YC



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