Cecil Moore wrote:
Mike Kaliski wrote:
and that the characteristic impedence will vary along an antennas length.

Well, that's obviously false. The characteristic
impedance of a horizontal wire above ground is
constant at 138*log(4D/d)

The characteristic impedance is not to be confused
with the voltage to current ratio existing on a
standing-wave antenna any more than the characteristic
impedance of a transmission line is to be confused
with the voltage to current radio existing along
its length when the SWR is not 1:1.

Interesting point.

When I use a gamma match on a 1/2 wave vertical with counterpoise, I
have always wondered about the 50ohm impedance point where the gamma
taps the element.

To end feed the antenna, an impedance of thousands of ohms is
encountered, a, seemingly, "strange" distance up the element (in regards
to total element length) and a 50 ohm impedance point is encountered
(needing only a series capacitive reactance to correct for the gamma
rods' inductive reactance.)

It would be interesting if I had a formula which would predict what
impedance would be encountered for all points along the element--know of
any?

I have looked at setting up such a formula, but frankly have been
unsuccessful ... and of course, it is given that antenna length IS
resonate for the frequency in question.

Regards,
JS