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Re: [TowerTalk] MACAntenna

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] MACAntenna
From: "Paul Christensen" <w9ac@arrl.net>
Date: Wed, 20 May 2009 11:00:33 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
> The antenna I saw at dayton looks like ladder line loops for each
> element with relays along each element to close the loops for each
> band selected.

>From the QST article on the dipole version of the antenna, one side of the 
ladder line forms an element while the other ladder line conductor is used 
to complete the relay return path.

> This is done with a relay control box. Seems to be a
> good idea but there is always compromise.  Relay failures and parts
> with each board, control box and power output limitations.

I could see this as a good alternative to something like the SteppIR if 
there was some means to control F/B, pattern, or some other electrical 
parameter.  But there isn't.  From what I can tell, there's no benefit over 
that of a well-designed, shortened trap or linear-loaded Yagi with 
negligible losses.

What's not known is the degree of loss due to their mechanical relay 
switching network and losses attributed to the line isolation system used to 
allow DC power-passing on the coaxial line.

Paul, W9AC 

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