Ian White GM3SEK wrote:
Now what happens if the load is not exactly 50 ohms?

If the feedline is 50 ohms, what happens is reflected
energy that is easily visible using a TDR, time domain
reflectometer.

One is that if the meter scale says "power", then there genuinely are
forward and reflected traveling waves of power on the line. In the "93 -
23 = 70W" example, the belief is that there genuinely is a power flow of
93W towards the load, only 70W of which is accepted and 23W is returned.

One correction. The Bird wattmeter is installed at a point
on the transmission line and it measures the power at that
point. What is traveling is the energy. Power is the number
of joules per second passing a fixed point. "Power flow" is
somewhat of a misnomer.

The other school of thought is that that's not true. The meter may
*read* more "forward power" than is actually being delivered to the
load, but that is a false indication because the instrument is not being
used in the situation for which the power scale was calibrated.

It certainly is being used in the situation for which it was
calibrated if the Z0 of the transmission line is 50 ohms.

On the other hand, we have yet to see an explanation in equivalent
physical detail that is based entirely and exclusively on the viewpoint
of travelling waves of power ...

Please give up on your misconception. Those are traveling waves
of *ENERGY*. Power is what is measured when traveling energy passes
a fixed point. Perhaps that is your whole point of confusion.
--
73, Cecil http://www.qsl.net/w5dxp