Richard Harrison wrote:

Keith wrote:
"Yes, indeed. But there is no power."

Actually I wrote much more than that and the stuff which preceded was
much more important.

Keith`s perception is flawed. He is addressing r-f with a d-c mindset.
R-F power flow does not stop at an SWR zero-voltage point. Like "Old Man
River" it just keeps rolling along.

P(t) = V(t) * I(t) is much more general than DC or sinusoidal RF. It
works
for any signal shape you choose, even non-repetitive ones.

It certainly works for my electic company who integrate P(t) and
regularly send me a bill.

The zero-voltage point exists because the phase relationship between two
oppositely traveling waves is fixed, and the zero-volts point is where
the vectors cancel.

You must simultaneously sense both waves to find a zero. Sensing either
wave alone finds no dip in voltage. Carramba!

From this response it is clear that you are not yet in group b).

But is it:
group a) P(t) is not always equal to V(t) * I(t); or
group c) energy can flow when P(t) is a constant 0
?

Or maybe my list is incomplete and there is a 4th option which I missed.

May I respectfully suggest that if you are having difficulty selecting
which option applies to your thinking (and yet can't produce a fourth
option), that you try to discover the source of your discomfort. From
there, enlightenment may arise.

For myself, I recognized the "double think" and so rejected c).
P(t) = V(t) * I(t) seemed so fundamental that it had to be accepted
thus I was forced to reject a).
This left only b). Although it rejects some of the often stated and
accepted explanations about transmission lines, it was the lesser
of the evils. Some thinking revealed the weaknesses in the 'often
stated and accepted' explanations and now all is consistent.

This process took some time, prompted and assisted by the never
ending arguments which go on in this group. So I do thank those
mis-guided souls who argue endlessly and the patient answerers
who respond mostly for the benefit of the lurker.

But be that as it may, do try and figure out whether option a),
b) or c) best describes your thinking. Only an increased
understanding can arise.

....Keith