"Jeff" wrote in
.com:


"
The power delivered to a load (of any kind) from a lossless
transmission line section, is the same as the power delivered by the
source.

So it is your contention that power is not reflected at a mismatch.
The wave certainly is so the power contained in the reflected portion
must be as well.

The danger in the "power is refelected at a mismatch" explanation, is
that it follows that power reflected at a mismatched antenna flows back
toward the transmitter and is at least partially absorbed in the PA as
heat. Though that is a popular belief, it is not supported by fact.

The power at a point in a transmission line is P=real(V*conjugate(I)).
This expands to four terms, and people arbitrarily allocate the terms
forward power and reflected power to just two of the four terms because
they happen to be VfIf and VrIr.


You assertion that you have travelling forward and reflected power
waves on the transmission line runs into a problem when you try to
analyse the combination of both at a point (eg the input to the line)
as power doesn't combine vectorially.

I was not trying to analyse the combination of any wave on the line
("power" waves, whatever they may be, or anything else), I was merely
noting that you can quantify and measure the power contained the both
the forward and reflected waves and they are real quantities.

The Bird 43 does not measure power directly, it responds to Vf or Vr
components at a point as explained in the article I quoted. The article
deals with the conditions under which readings can be converted to power,
and whether forward power or reverse power are of themselves meaninful.

If you have read it and disagree, then thats ok. If you can identify
flaws in the article, constructive feedback is welcome.

Owen