Gene, W4SZ wrote:
"However, the physical entities do not have two values at once in the
same time and place."

Richard Harrison wrote:
You can measure each of the two simultaneous constituents with the right
equipment. A Bird Thruline wattmeter uses a directional coupler to
separate forward direction power from reverse direction power. These are
obbtainable at the same time and place anywhere in a 50-ohm coax line.
Individual volts and amps in each direction are easily calcuable from
the powers indicated in each direction.

That's not true.

The directional coupler in a Bird meter samples the across vector
(voltage) from a capacitive divider and adds it to a sample voltage of
the through vector (current) from a current transformer in a
predetermined ratio. After that sum, the output is rectified.

I can place it in a system with NO standing waves and it will show
standing waves. I can place it in a system with standing waves and have
it show NO standing waves. It does not measure standing waves, it
simply measures the ratio and phase of voltage and current at one point
in the transmission line.

There can NEVER be current flowing at that point in two directions at
the same instant of time, and the Bird does not even contain a system
that samples standing waves.

Now I can build a piece of test gear that does directly read standing
waves, but it requires a line sampling lwength of at least 1/4 wl.
Such a device would be totally independent of the actual operating
impedance, and could read either current or voltage.

The Bird meter is NOT that type of unit.

73 Tom