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Re: [TowerTalk] Change in Frequency As Antenna Height Rises

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Change in Frequency As Antenna Height Rises
From: "Ed Sawyer" <sawyered@earthlink.net>
Reply-to: sawyered@earthlink.net
Date: Wed, 1 Jun 2016 10:24:37 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I have the Force 12 EF240X.  This is the wire loaded elements that are about
45 ft long and a 24ft boom.  I have tuned this antenna and have found the
resonance (not the 1:1 SWR) changes pretty significantly from 15 ft to 35 ft
to 80 ft.  I don't have my original notes, but I recall seeing at least
100khz total shift.  However, the 35 to 80 ft shift was maybe 20 - 25khz vs
the 15 to 35 ft shift being the rest.  I always attributed it to the
additional ground coupling changing the net "loading" on the shortened
elements that got less impactful as it got higher.

 

I have not used the antenna in a couple of years.  It was potent but the
construction weaknesses were an issue.  Its on the "refurb" list but not a
priority.

 

Ed  N1UR

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