Mike Kaliski wrote:
Are you sure you are not confusing the characteristic impedance of a
dipole antenna with the characteristic impedence of an open feed line?
One is constant, the other appears to vary along its length. A dipole
antenna has low impedence at a centre feed point and high impedence at
it's ends.

The feedpoint impedance of a stub is NOT the same thing
as the Z0 of the stub. The feedpoint impedance of an
antenna is NOT the same thing as the Z0 of the antenna.

The characteristic impedance of a #14 wire 30 feet above
the ground is close to constant at 600 ohms. The formula
for a single-wire transmission line is 138*log(4D/d).
A horizontal dipole is nothing more than a single-wire
transmission line which is known to be lossy.

The characteristic impedance of a transmission line is
constant. If the SWR 1, the voltage to current
ratio varies along its length. That varying impedance
(V/I) is NOT the characteristic impedance which is
constant.

The characteristic impedance of a horizontal dipole is
~constant. Since a dipole is a standing wave antenna,
the voltage to current ratio varies along its length.
That varying impedance (V/I) is NOT the characteristic
impedance which is relatively constant for a horizontal
wire.
--
73, Cecil http://www.w5dxp.com