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.
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.
Yet lossy lines are just what we're talking about now, isn't it?
Yes, and I am in the process of trying to understand them.
So what are the "forward power" and "reverse power" for lossy lines? Any
explanation for why they vary (other than with the expected attenuation)
with position along the line?
I don't know, yet.
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.
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.
--
73, Cecil
http://www.qsl.net/w5dxp
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