Richard Harrison wrote:
Roy Lewallen, W7EL wrote:
"A real analysis of energy flow involves calculating the power at
various points and times in the circuit or transmission line of
interest."

Yes. Bird Electronic Corporation has done a good job of this with its
"Thruline" wattmeter for several decades.
. . .

No, the Bird wattmeter measures only the average power and only at one
point. That's vastly different from what I described, which is
instantaneous power as a function of time at many points along the line.
A complete analysis of energy flow would include equations for the power
as a function of time and position. You're sadly mistaken if you think
you're getting this information from your Bird wattmeter.

Roy Lewallen, W7EL