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Re: Topband: invL experiments

To: <armin.ficza@nsn.com>, <topband@contesting.com>
Subject: Re: Topband: invL experiments
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Sat, 28 Apr 2007 10:43:51 -0400
List-post: <mailto:topband@contesting.com>
> Could somebody explain to me:
> Which one is the better option.
> Next thing is that theoretically 3m trim would be needed, 
> but had to cut
> 8m. Why? Is there some coupling active?

Yes, to earth. The radials are very tightly coupled to the 
earth below them. Also, unless you have a common mode choke 
on the feedline at the feedpoint the feedline and everything 
connected to it is a big part of the radial system. This is 
because the antenna only has two radials. So the feedline is 
really one of three radials unless it is decoupled.

> Does this antenna act as a vertical dipole ( with capacity 
> hats) now?

Probably not. It acts as an inverted L with poor to mediocre 
ground system.

73 Tom 


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