Roger wrote:

What you are forgetting is that power is also found from Power = V^2/Zo
and Power = I^2*Zo. More accurately, on the standing wave line,
Power = (V^2 + I^2)/Zo. This is why a SWR power meter detects both
current and voltage from the standing wave.

This will also be true on the quarter wave stub, which is really 1/2
wave length long electrically, when you consider the time required for
the wave to go from initiation to end and back to beginning point.
Power is stored on the stub during the 1/2 cycle energized, and then
that stored power acts to present either a high or low impedance to
the next 1/2 cycle, depending upon whether the stub is shorted or open.

I think you did a very good job in building your theory. It was only
at the end (where I think we need to consider additional ways of
measuring power) that we disagree.

73, Roger, W7WKB

Haste makes waste, and errors as well. The standing wave power
equation is incorrect. It should read "Power = V^2 / Zo + I^2 * Zo"

Sorry for any inconvenience, and for the several postings it will
probably stimulate.

73, Roger, W7WKB

Sorry, neither is correct.

Z0 is the ratio of V to I of a traveling wave. It's not the ratio of V
to I of the total of a forward and reverse wave (which has been
carelessly called "the standing wave" in this thread). If you want to
calculate power as V^2 / R or I^2 * R, you have to use Re(V/I) as the
value of R -- then you will, as you must, get the same result using V *
I, I^2 * R, or V^2 / R. As any text can tell you, the value of Z (ratio
of V to I) varies along a line which has reflected waves (i.e., has a
standing wave). If you use Z0 for the calculation in those cases, you
get results which have no meaning or physical significance.

V^2 / R + I^2 * R doesn't give power, using either Z0 or V/I as R. I'm
curious as to where that equation came from or how it was derived.

Roy Lewallen, W7EL