Walter Maxwell wrote:
Cecil Moore wrote:
Proving that "Power in the reflected wave" is common
usage in RF engineering.
Jim, I'm sure you'll agree that voltage is reflected, and that current
is also reflected. Then isn't the product of voltage and current
power?
I think I understand Jim's point that power is measured
relative to a stationary point or plane. The Bird wattmeter
is stationary in the transmission line and measures the
average energy/time flowing through it. Average power is
averaged over at least one complete cycle. It is hard to
visualize an average power meter measurement while the meter
is moving with the wave - admittedly an esoteric point and
not likely to have any effect on common usage.
Consider that it is the instantaneous value of voltage and
current that is reflected (actually the instantaneous E-field
and H-field). The RMS value of voltage and current is not
what is actually reflected in reality. But again, shortcuts
and common usage rule the day.
--
73, Cecil
http://www.qsl.net/w5dxp
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