Several posters have recommended a simple series coil for matching.
But of course, you'll never get lower than the resistive component of
the feedpoint impedance that way. At least one suggested a tapped
coil, and that can give you a good match and has the advantage of
DC-grounding the lightening ro...I mean radiating element.

Another alternative is a shunt coil to ground and a series capacitor
off to the feedline; that gives you the grounding and also lowers the
low-frequency coupling to the feedline. If Reg's suggested 110-j386
is correct for your case, you can get a match to 50 ohms at 24MHz with
a 1.1 microhenry shunt coil and 25pF series capacitor. The Q should
be around 5, not much higher than the antenna itself but can lead to
fairly high voltage across the cap. Don't leave it exposed to rain
:-) (That's an advantage of the tapped coil: less suseptable to
weather problems.)

But beware...the range of impedances I've seen posted suggests your
installation may be somewhat different.


Cheers,
Tom


Larry D wrote in message ...
I want to construct a 5/8 wave ground plane for 24 MHz.
I am OK with the dimensions, but I can't get a grip on what
the impedance at the feedpoint will be. Even the ARRL
antenna book hasn't been much help.

Can anyone tell me the impedance I can expect to see,
also any tips on matching it? Thanks!

Larry DiGioia N8KU
N8KU at longwire.com