Cecil Moore wrote:

Jim Kelley wrote:
That angle is the 'phase' of the current standing wave as a function of
position, not to be confused with the phase of the current with respect
to voltage. Roger?

Since any reference to voltage on an antenna seems to be verboten, I
have avoided any such reference.

I can understand how at DC, references to current in a dipole might be
verboten. :-)

I wonder if voltage on a dipole could be roughly likened to transverse
velocity at various points along a whip.

Don't you just love the phrase, "It is generally assumed ..."?

I guess it allows: 'I'm not responsible should it turn out not to be a
good assumption'. :-)

For that general assumption to be true, the reflected current would have
to equal the forward current on a standing-wave antenna. But we know it
doesn't. However, this implies that the reflected current arriving back
at the feedpoint is not extremely/severely attenuated.

Seems to me it just implies that current at the end of a dipole isn't
really zero.

Assume the Z0 of a traveling-wave dipole is 600 ohms. The ratio of forward
voltage to forward current is 600 ohms. The ratio of reflected voltage to
reflected current is 600 ohms. Assume the feedpoint current is one amp and
the feedpoint voltage is 50 volts. Assume the forward current and the reflected
current are in phase at the feedpoint. Assume the forward voltage and reflected
voltage are 180 degrees out of phase at the feedpoint. This is enough information
to solve for the ratio of forward current to reflected current at the feedpoint.
Assuming the net current is one amp at the feedpoint, I get 0.542 amps for
the forward current and 0.458 amps for the reflected current, i.e. the reflected
current is 85% of the value of the forward current. Remember, that is a ballpark
estimate.

50 volts difference across a 600 ohm impedance, over 2, plus and minus
half an amp.

That means the current only decreases by 15% in its round trip to the
end of the antenna and back.

I think it may actually make many round trips. There may be multiple
reflections.

The argument seems to occur due to the ignoring of the component waves
on a standing wave antenna. Such is the steady-state model seduction attended
by its sacred cows.

Well, you'll either have to write out everything as a series, which is a
lot of busy work, or use the steady state equivalent.

So what does all this say about reflectivity at the end of the dipole?
;-)

73, Jim AC6XG