I've remember some "no ground" 1/2-wave VHF verticals (Larsen, I think)
which had a small tapped coil at the bottom. I think they were
intended for mobile use with cars having fiberglass bodies. The shield
was connected to the bottom of the coil and the center conductor was
connected to the tap. The top of the coil is at a high impedance and
provides a voltage feed to the vertical (if the dimensions of the
tapped coil are such that it is self-resonant at the operating
frequency, it would be the electrical equivalent of the quarter-wave
stub of a J-pole). What you describe is probably similar.
Bob, N7XY
On Tue, Mar 18, 2003 at 12:49:02PM +0000, Robert Thain wrote:
> Hello (again),
>
> I've received just one or 2 replies on my original
> mail, (thanks for those).
>
> How do those end fed 1/2 wave "CB" verticals work,
> with no ground ?
>
> The closest I have found is a J-pole, which is close
> but not what I'm looking for.
>
> To end feed a 1/2 wave it has to be a high voltage
> feed and not the traditional current feed.
>
> I remember from a long time back that these antennas
> had a little air spaced coil at the feed point and no
> ground radials etc.
>
> Help please,
>
> Robert
> G0HGW
>
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