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Re: [TowerTalk] 80M Delta Loop

To: towertalk reflector <towertalk@contesting.com>
Subject: Re: [TowerTalk] 80M Delta Loop
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Wed, 24 Jul 2024 12:41:36 -0700
List-post: <mailto:towertalk@contesting.com>
On 7/24/2024 11:31 AM, kq2m@kq2m.com wrote:
> One antenna that does work well even over poor ground is a 4-square with elevated radials, preferably above .05 wavelength in height.

Poor soil degrades the efficiency of vertically polarized antennas both under the antenna AND in the far field, where the ground reflection that reinforces the direct wave is created. Radial systems affect ONLY what happens under the radials -- they screen the direct field of the antenna from the lossy earth, and give the antenna a low resistance path for its return current. That's ALL that they do. They cannot compensate for lossy ground in the far field.

But ground characteristics DO vary with location, even with lousy ground under the antenna, good ground in the far field can support the needed reflection, making the antenna work well. That's the classic case of a vertical near salt water. And N6BT, well-known for his "Team Vertical" setups, has recently done field measurements with a drone to show that a vertical very close to a drop-off (his testing was on a mesa in AZ) produces a very strong signal in the direction of the dropoff. He first showed this work as part of the Pacificon Antenna Forum about five years ago, to which we both often contributed.

73, Jim K9YC

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