Tarmo Tammaru wrote:
Try this out. You have an amplifier of unknown source impedance connected
through a directional meter to a 1/4 wavelength line that is shorted at the
far end. Without knowing about SWR, you know (because you are a ham radio
operator) that the amp is driving an infinite impedance, and delivering 0
power. Now if you adjust the amp so the meter reads 100W in both directions,
the amp is still delivering 0 power, and 100% of the reflected wave is
rereflected. Where did the 100W come from? the amp delivered it during the
first 1/2 cycle after it was turned on. It didn't "know" the line was
shorted until the first reflection came back.

How do you know that the amplifier is not "delivering" 100W of forward power
and dissipating 100W of reflected power (as it would with a circulator+load)?
How do you prove that the impedance looking back into the amp is zero, infinity,
or purely reactive? Doesn't it have everything to do with the arbitrary
definition of "delivered" which doesn't necessarily match reality?
--
73, Cecil http://www.qsl.net/w5dxp



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