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Topband: DOUBLED RADIALS

To: <topband@contesting.com>
Subject: Topband: DOUBLED RADIALS
From: w8ji@contesting.com (Tom Rauch)
Date: Sun, 29 Oct 2000 06:27:08 -0500
> If you "double up" a 1/4 wavelength of radial in the same slit except for
> 10-15 feet at the end closest to the antenna, is the net effect
> approximately 1/8 wavelength of wire in the ground or is it something
> between the full 1/4 length and 1/8th?  It obviously won't be as efficient
> as it would if the whole length was stretched out but would there be so
> much coupling between the wire doubled back on itself that it would be a
> waste of wire?

1/4wl of wire in a 1/8th wl long area is a 1/8 wl radial. 

The primary "job" of a radial is to spread the electric (voltage) and 
magnetic (current) fields over a large area, so losses are reduced in 
the lossy media below and around the antenna. The shorter and 
fewer the radials, the more concentrated the fields and the lossier 
the system.

Folding the wire up or loading mainly changes the impedance 
looking into the radials from the feedpoint connection, not so much 
the system loss. To reduce system loss the radial system has to 
be made larger, to reduce the voltage and current in each area of 
the radial system and the fields around the radials.
   
73, Tom W8JI
w8ji@contesting.com


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