-----Original Message-----
>From: Red <RedHaines@centurytel.net>
>Sent: May 8, 2006 12:30 PM
>To: TowerTalk <towertalk@contesting.com>
>Subject: [TowerTalk] Radials for a 4 sq system?
>
>Hello, TTers;
>
>Regarding ground level or slightly below ground radials under a vertical
>antenna:
>
>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.
>
<snip>
Excellent description. The capacitive coupling conceptualization is a good one.
Jim
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