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[TowerTalk] Vertical ground radials

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Subject: [TowerTalk] Vertical ground radials
From: (Tom Rauch)
Date: Thu, 25 Oct 2001 11:39:00 -0400
> One question that arises when using ground radials is:  assuming you
> are using insulated wire for the radials (which I am), should the ends
> of the wire be left floating or be grounded (or does it really not
> make any difference). 

It won't make any difference at all one way or another. 
> The one area of interest and differing opinion is in the number of
> radials to use.   Guy (K2AV) pretty much sumed it up by saying; "Quite
> a few will say if you put down 60 radials with most directions out
> 130', your antenna will play very well. EVERYONE will say if you put
> down 120 radials with most directions out 130', your antenna will play
> very well".

The 120 radial myth is mostly based on folklore, and 
misunderstanding of what the FCC suggests....not on 

The FCC suggests using 120  HALF-wave radials for BC station 
because they want a lot of headroom as the system deteriorates, 
and because stability of elements is critical in BC work with 
directional arrays.

If you look at the RCA study "Ground Systems as a Factor in 
Antenna Efficiency", you will see the measurements reveal the 

1.) Once radials ends are about .025 WL apart, NOTHING is 
gained by interlacing more radials.

2.) The shorter the vertical and the lower loss the loading system  
the more critical the ground system is.

3.) Ground screens make no difference at all when the radials have 
reasonable efficiency.

Many people try to copy what BC stations do, or what others say 
BC stations do, without understanding why certain things are done.

That is why you get two answer based on what 
actually happens while the other is based on what we might think 
happens if we aren't or haven't been involved in BC array design.
73, Tom W8JI 

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