[TowerTalk] Definition of Ground Screen vs. Radials, Request for Information

[Tom Rauch]

> Nomex e-mail program is ON.  Flame away, but remember, some Towertalkians
> may be under 21.
> 
> 73,
> Jan, KX2A

Hi Jan,

I checked my Communications Standard Dictionary and another 
standard dictionary:

1.) A "screen" is defined as "a shield or filter". A radial system 
behaves as a screen by filtering or shielding the earth from the 
effects of fields around the antenna, so does a counterpoise if it is 
large enough.  

2.) "Radials" are defined as "conductors extending in radial 
directions used as a ground, counterpoise, or earth connection in 
an antenna system".  A screen that doesn't have radial conductors 
can't be a radial system, even though the radial system can be a 
screen or counterpoise. 

3.) A "ground" is defined as a "direct connection to a conductor in 
an electrical circuit, either accidental or on purpose".  

I can ground my screwdriver blade to my antenna, but the antenna 
won't be grounded. 

4.) A counterpoise is "a conductor or system of conductors used 
as a substitute earth or ground in an antenna system."

I can put a screen below a dipole, and it will establish a "substitute 
earth" or counterpoise even if it has no connection.  

5.) "Earth" is defined a "point in an electrical circuit that is 
connected by a zero resistance path directly into or under the 
ground". Earth is also defined as "one part of an electrical circuit, 
such as in a ground return. A perfect earth is at zero potential no 
matter how much current is forced into it".

Obviously there is no such thing as an "earth" by the first criteria, 
so an earth can only be a ground return! We can't have a perfect 
earth. No matter how we try.

I hope this clears up the needless confusion or ambiguity in 
definitions.
73, Tom W8JI
w8ji@contesting.com

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