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Old June 26th 10, 02:05 PM posted to rec.radio.amateur.antenna
Cecil Moore Cecil Moore is offline
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First recorded activity by RadioBanter: Aug 2006
Posts: 572
Default what happens to reflected energy ?

On Jun 25, 4:00*pm, Keith Dysart wrote:
That's the time domain. Variation in the instantaneous energy flow.


What you seem to be missing is that the *energy content* of power
(total joules) must be conserved but the instantaneous power (joules/
second) does not have to be conserved as you have argued numerous
times in numerous examples. The only question that needs to be
answered is: In a system designed to eliminate reflections and
interference, does all the reflected energy eventually get dissipated
in the source resistor. The answer is yes because there is nowhere
else for it to go. There is no conservation of power principle and
that includes instantaneous power. So it is irrelevant what/where
instantaneous power might do/go during a single cycle.

Now I understand that instantaneous power dictates some physical
design considerations as in waveguides. But since instantaneous power
does not fall under the conservation of energy principle, it is simply
irrelevant to the present discussion. What happens over a complete
cycle is what is relevant. However, in any and every case, it is
energy that is conserved, not power. How many joules are in that dt
sliver of time when the instantaneous power is 100 watts? It's those
joules that must be conserved, not the instantaneous power.

You didn't answer my previous question. If you measure 100 watts of
instantaneous power at 100 places within an inch of each other, does
that mean there is 10000 watts of instantaneous power in that one inch
of wire? That is the only logical conclusion based on your argument
and assertions. Any argument based on the conservation of power is
doomed to fail. Please get real.

Not quite
'as useless as tits on a boar hog, or as Hecht said, putting it
mildly: "of limited utility"'.


One could argue that tits on a boar hog are not completely useless
and, therefore, instantaneous energy is exactly as useless (or exactly
as useful) as tits on a boar hog. (Hint: Without the existence of the
tit gene in the male, female hogs would probably not have tits.)
--
73, Cecil, w5dxp.com