Cecil Moore wrote:
Tom Donaly wrote:
O.k., Cecil, you said it, now prove it. There's no requirement
for a 90 degree phase shift when you do the math.

Are you using the equation for forward and reflected
current? If not, you need to do so. The phase shift
is not in the standing-wave current. Standing-wave
current phase is fixed with respect to the source.
Absolutely *nothing* happens to the standing-wave
current at the impedance discontinuity.

The reflected current is known to be in phase with
the forward current at the feedpoint. The forward
current is reflected at the tip of the antenna and
undergoes a 180 degree phase shift. Something must
account for the other 180 degrees or else the
feedpoint impedance would not be resistive. I am
working on a graphic that illustrates what happens
at the impedance discontinuity.

Please enlighten us on how the reflected current
gets back in phase with the forward current without
undergoing a phase shift of 180 degrees in its
round-trip path. It is my understanding that the
forward phasor rotates in one direction while the
reflected phasor rotates in the opposite direction.
The key concept there is that a phasor is always
rotating.

I have waded through the math before but I cannot
locate my notes after moving. If you can figure
out a reasonable answer to the above question, I
will certainly consider it.

How about answering the other part of my post, Cecil.
I didn't use reflection mechanics to reach my conclusion.
I did use two port ABCD parameters (the hard way) which can
be derived from reflection mechanics. Anyway, you're being too
simple. If you're going to use reflection mechanics, you have to
account for all the reflections, and you have to explain yourself
each step of the way. Anyway, destroy a few brain cells
thinking about the other part of my post and get back to me.
73,
Tom Donaly, KA6RUH