Topband: trimming elevated radials

Tom W8JI w8ji at
Sun Mar 31 20:45:17 EDT 2013

> What is the preferred method of tuning elevated radials for uniformity?

Jeff and all,

It takes two halves of a system to make a whole system. This means the 
vertical affects the radial resonant length, just as the radial length would 
affect the resonance of the vertical when they are in a system.

Looking for nulls and peaks doesn't work, because voltage or current changes 
so slowly.

What works for a first approximation is tuning the radials like dipoles, 
using opposing radials. Then, after the initial four or more radials are 
tuned like dipoles with ach half equal length, look at ONE radial at a time 
against all of the remaining radials tied together as a counterpoise. This 
keeps the vertical, which is probably not resonant yet, out of the picture. 
This sorts out any radials that are resonant "length flyers".

This is the procedure I always followed.

If the radials are resonant, and if you have enough of them, radial-to-earth 
voltage will be a minimum at the feedpoint and bandwidth will be a maximum. 
Bandwidth will generally get wider with more radials because radial system 
sharpness will decrease, even as loss decreases. The more radials you use, 
the less critical resonance and earth isolation becomes.

After the radials are tuned and verified, the vertical can be tuned or 

Or you can just cut them all to one length, and without a known reference 
system you would have no idea if it didn't work as well as possible. If you 
get a few good reports, or work a new country, it would prove a 20 dB 
increase. :-)

73 Tom 

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