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[TowerTalk] Ground screen ????

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Subject: [TowerTalk] Ground screen ????
From: "Jon Suehiro" <nn5t@attglobal.net>
Date: Thu, 3 Mar 2016 04:07:59 -0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Just be aware of the radiation patterns.

 

When I had 1/4 WL Inv L (65' vertical section), I was unable to obtain low
V.S.W.R. since expected radiation resistance was 12 ~ 15Ohms and required to
use antenna tuner.

 

Upon the modification to 3/8 WL with 150pF VC at the feed point, obtained
perfect V.S.W.R. but the antenna completely turned into local only and no
DX. Simulation indicated the radiation pattern was straight up like low DP
and not like typical vertical pattern.

 

Addition of un-un such 25Ohm (or even 12.5Ohm) to 50 Ohm at the feeding
point should be helpful to your situation.

 

GL de NN5T Jon

 

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