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Richard Clark · September 27th 10, 06:35 PM posted to rec.radio.amateur.antenna

On Mon, 27 Sep 2010 03:26:52 -0700 (PDT), wrote:

I preferred my plastic bugcatchers so I could
use a higher coil location for more efficiency and better current
distribution.

Hi Mark,

That was my point about the screwdriver being run as a elevated
vertical dipole.

In point of fact, that is how it is designed to work (after a
fashion). The bumper mount (or car chassis attachment) is the
grounded lower element, then we have a coil of variable length,
followed by the upper element with the feed hidden inside the lower
element.

I don't see that radials add anything to this. Their radiative
contributions all cancel anyway if they are straight out, and they add
towards approximating a vertical element if they droop. If,
perchance, you wanted short radials (straight out or drooping), then
it would only require more inductance to match the capacitive
reactance. Push the tune button and walla! (as the french would say),
more turns of the coil out there. And for being a sleeve dipole, that
coil would be quite high - current distribution would come out in the
wash.

73's
Richard Clark, KB7QHC