[TowerTalk] Radials for a 4 sq system?

Jim Lux jimlux at earthlink.net
Mon May 8 18:41:56 EDT 2006

-----Original Message-----
>From: Red <RedHaines at centurytel.net>
>Sent: May 8, 2006 12:30 PM
>To: TowerTalk <towertalk at contesting.com>
>Subject: [TowerTalk] Radials for a 4 sq system?
>Hello, TTers;
>Regarding ground level or slightly below ground radials under a vertical 
>They don't work like a ground plane or counterpoise, in which dimensions 
>are essential to resonance of the antenna system.
>Think of the radials as being one plate of a capacitor.  The other plate 
>is earth.  The purpose of the radials, when on or in the ground, is to 
>couple the feedline to ground, which serves as one element of a dipole 
>antenna (The vertical is the other element.).  They reduce the 
>resistance losses associated with antenna current in the earth, by 
>spreading that current over a large area of the ground rather than 
>letting it be concentrated into a small volume of earth surrounding a 
>ground rod. 
>They do not act as resonant antenna elements.  Their length is not a 
>critical part of antenna tuning.  Under a 1/4 wave vertical, they are in 
>the area of highest current density, the area nearest the vertical 
>element.  That is the reason that a limited amount of wire is applied 
>most effectively in making a large number of short radials, even if they 
>don't reach very far from the antenna.


Excellent description.  The capacitive coupling conceptualization is a good one.


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