Tdonaly wrote:
Please reference Fig 1, page 2-2, in the 15th edition of the ARRL
Antenna Book. "Current and voltage distribution on a 1/2WL wire.

The RMS (or peak) values of the voltages at the ends of the dipole
are maximum and 180 degrees out of phase. The ratio of net voltage to
net current is the impedance anywhere along the wire.

Cecil, that picture is a gross simplification. In order to show that there's
a unique voltage between the ends of a dipole, you first have to show that
the time-varying electric field between those ends is conservative.

Each leg of a dipole is a one-wire transmission line with a Z0 around
600 ohms (according to Reg). These kinds of antennas are known as
"standing-wave" antennas because of (surprise) their standing waves as
depicted by the diagram in the ARRL Antenna Book. The center feedpoint
impedance is not 600 ohms because of the reflections from the ends.
Feedpoint impedance equals (Vfwd+Vref)/(Ifwd/Iref), just like a
transmission line.

The forward voltage wave hits an open circuit at the end of the dipole.
The reflected voltage wave possesses reversed direction and reversed phase,
just like an open circuit in a transmission line. The net voltage at the end
of a dipole is 2 times the forward voltage, just like an open circuit in
a transmission line. Thus, standing waves are created on the antenna wires.
The two ends of the dipole are also 180 degrees out of phase.

If you curve a dipole into a circle and measure the end-to-end voltage
with an RF voltmeter, you will get a voltage in the ballpark of four
times the forward voltage on the antenna.

You can use a fluorescent light bulb to locate the maximum electric
field. That will be at the ends of a 1/2WL dipole or at the top of
a 1/4WL monopole. I'm surprised you guys haven't ever done that.
--
73, Cecil, W5DXP