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Topband: Zip cord receive antenna.

To: <topband@contesting.com>
Subject: Topband: Zip cord receive antenna.
From: W8JI@contesting.com (Tom Rauch)
Date: Fri, 4 Oct 2002 09:35:00 -0400
Hi Bob,

> I should try for receiving on my small city lot. He described it as
> 200feet of lamp cord 18ga with a 200 ohm resistor on one end and a 300
> ohm to 75 ohm tv balun on the other. Where can I find more information
> on this?

Antennas like that (and the Snake antenna) fall into the class of 
accidental antennas that are not based on any logical design or 
thought. 

They work solely by accident, because of actual flaws in the system. 

For example, if the zip cord and balun were perfect, the antenna 
would be absolutely stone-deaf for receiving. You would not be able 
to hear ANYTHING on the antenna, not even very strong local signals. 

The antenna might hear something because TV baluns are not perfect, 
especially since they are only designed to work above 50MHz. The zip 
cord laying on the ground also might become slightly unbalanced, and 
that may allow signals (and noise) to leak into the line. It is the 
combination of imperfections that allow signals and noise into the 
"antenna".

Because it is just something that receives through defects or flaws 
in the design or the components used, it is totally unpredictable. 
You will just have to try it, and see if it does anything at all. My 
bet is if it does anything at all, you will need a big amplifier with 
it....unless you happen to get a really exceptionally bad balun. Then 
it would work exactly like a random wire laying on the ground.      
73, Tom W8JI
W8JI@contesting.com 


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