On Jun 18, 6:00*am, Keith Dysart wrote:
"Is this a situation
where the computed reflected power represents something real?"
because if it does not, the original question is moot.

It certainly depends upon your definition of "power" and that
definition is different between pure physics and RF engineering. One
of the accepted definitions of "power" in "The IEEE Dictionary"
contradicts the definition of "power" given in my college physics
book. "The IEEE Dictionary" says that flowing energy passing a fixed
measurement point is power, by definition.

If there is anything at all that can be measured, it must necessarily
contain energy. If the EM energy is moving, it is power, by IEEE
definition. If you disagree, take it up with The IEEE.

So the actual question that needs to be answered is: Does the
electromagnetic reflected wave contain energy traveling at the speed
of light in the medium? The answer is yes, being photonic in nature,
an EM wave must necessarily contain an ExH power density and,
consisting of photons, must necessarily be traveling at the speed of
light in the medium. The EM wave will continue to travel in the
direction of energy flow at the speed of light in the medium until it
encounters an impedance discontinuity which causes a reflection and/or
interference.

There is really no difference in a forward wave and a reflected wave
except for the direction of travel. They both contain an associated
ExH power density. One can set up identical signal generators at each
end of a transmission line to emulate forward and reflected waves.
Which generator yields forward waves and which generator yields
reflected waves? It doesn't really matter because direction is only a
convention.
--
73, Cecil, w5dxp.com