[TowerTalk] info on radials repartition...

Jim Brown jim at audiosystemsgroup.com
Fri Apr 13 11:10:45 EDT 2007


On Fri, 13 Apr 2007 13:11:31 +0000, VE2RYY wrote:

>I am using a 2 element phased vertical (towers) on 80 meters.There
>are about 75 radials under each tower for 80M.
>Now I want to use only one of these towers  for 160 meter

The potential problem is that if you add radials to only one tower, 
the DIFFERENCE between the two towers will screw up the pattern on 
80 by unbalancing that array. If it were my antenna system, I would 
either leave it alone or add radials to both towers as symmetrically 
as possible. 

I'm assuming that your radials are on the ground, not elevated. On-
the-ground radials do not resonate -- they are simply a path for 
return current from the antenna, and more is better. All the science 
(as opposed to war stories) I've seen on non-elevated radials says 
that for a single tower, more is better, more closer to the tower is 
better, and longer is better, but that adding 16 or 32 1/4 wave 
radials to 75 1/8 wave radials is not likely to make a LARGE 
difference (I'd guess less than a dB for adding 16 based on data 
I've seen). The current version (20th) of the ARRL Antenna Book has 
a particularly good discussion of this. 

73,

Jim Brown K9YC




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