Cecil Moore wrote:
Roy Lewallen wrote:

I didn't, and don't, claim to have derived a "power reflection
coefficient". What I calculated was the ratio of reflected voltage to
forward voltage at the load, and called its magnitude rho. If there's
any step in the analysis that's unclear, I'll be happy to explain it
in more detail.


What you apparently calculated is s11 which is not always equal to rho.

I calculated the ratio of the reflected to forward voltage at the load,
and called its magnitude rho. If you have some other "rho" you want to
argue about, please call it something else.


What I have calculated is the ratio of reflected voltage to forward
voltage at the load, no more and no less.


No, you have calculated the ratio of one of the reflected voltages to
one of the forward voltages. I believe you have calculated the ratio
of s21*a1 to s12*a2 when you should be calculating the ratio of
(s11*a1+s12*a2) to (s21*a1+s22*a2). You simply omitted half the terms.


Please repeat my analysis, including the voltages or currents which were
omitted, and explain why they should be included. I used standard steady
state analysis, which infers one forward traveling voltage and current
wave, and one reverse traveling voltage and current wave. Although the
physical meaning of multiple traveling forward and reverse waves in
steady state gets a little hazy to me, I don't think there's anything in
principal that prevents you from assuming any number of forward and
reverse voltage an current waves you'd like, calculating reflection
coefficients for each pair, and adding them all up to get the total.
It'll be interesting to see how you choose to do it.

Of course, by choosing the pairs carefully, you can probably assure that
the magnitude of the reflection coefficient for any pair doesn't exceed
one. I'm not sure what that means or proves, but by all means have at it.

. . .

I'm sure that with enough s parameter and optics references, the facts
of the matter can be satisfactorily obscured.


It is you who is using an s-, h-, y-, z-, or other-parameter analysis
and are inadvertently obscuring the facts. You left out half the voltage
terms that should be included in the forward voltage and reflected
voltage. Add all the reflected voltages together. Add all the forward
voltages together. Divide the total reflected voltage by the total
forward voltage.

What the heck are you talking about? Just where in the analysis do you
see any s, h, y, or z parameter? I did calculate an impedance here and
there from voltages and currents -- is that some kind of a no-no in your
eyes?

Again, please show your analysis with the "missing" terms (that is,
voltages and currents) included.

Your view of how average powers add and travel do force that
restriction. I'm looking forward to your alternative analysis, which
shows the voltages, currents, and powers at both ends of the line
while simultaneously satisfying your notion of how average powers
interact.


I think all that is built into your analysis. When you include all the
necessary terms, I will be surprised if everything doesn't fall out
consistently.

Well, good. So show us.

Roy Lewallen, W7EL