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Re: [TowerTalk] Measuring resonance of a yagi element

To: "Tom Hellem" <tom.hellem@gmail.com>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] Measuring resonance of a yagi element
From: Ron W8RJL via TowerTalk <towertalk@contesting.com>
Reply-to: Ron W8RJL <youngron@verizon.net>
Date: Tue, 21 Apr 2020 23:34:35 -0700
List-post: <mailto:towertalk@contesting.com>
Tom,
Remember to get an accurate measure of resonant frequency the element will need to be at a height above ground where used. If you measure it at stepladder height it will be lower in freq than when up on the tower. I guess I am old school but there are many good designs in the antenna handbooks by ARRL and W6SAI and others. I realize everything these days is computer designed but my old 3 element 26 foot boom 20 meter Yagi built with handbook data work pretty darn good. I also interlaced 4 elements for 15 meters on the same boom. It worked great and all with data from handbooks.
73 and GL on your project.
Ron W8RJL

----- Original Message ----- From: "Tom Hellem" <tom.hellem@gmail.com>
To: <towertalk@contesting.com>
Sent: Tuesday, April 21, 2020 6:02 PM
Subject: [TowerTalk] Measuring resonance of a yagi element


I would like to measure the self-resonant frequency of the reflector on a
home made 20 meter yagi. It seems obvious the best way would probably be to
open it up at the center and make it into a split dipole element and hook
up my analyzer. However I would like to avoid cutting it and dealing with
splicing it back together again. Can anyone suggest another way to
accomplish my objective? The reason for doing this is because it is
apparent from modeling in EZNEC that the
length of the reflector is critical to the performance parameters of the
antenna, e.g. gain, F/B, bandwith, etc., and it looks to me like it doesn't
take much of a change in the length of the element

Thanks in advance for any replies.

Tom K0SN
Missoula, MT
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