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Old June 10th 05, 05:22 AM
Cecil Moore
 
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Roy Lewallen wrote:
I've explained how I calculated how much energy is stored in the
transmission line. The movement of energy within the line is complex; in
the abbreviated analysis I've had time to do so far, it sloshes back and
forth in regions within the line.


From where to where at what speed? Sloshing sounds like a
violation of the conservation of momentum. What force changes
the direction of the slosh? How much efficiency is lost in
the energy required to change sloshing directions?

It does not travel in waves of average
power, bouncing back and forth, and believing so isn't necessary in
order comply with energy conservation.


Nothing RF travels in waves of average power. Average power is
just our simplified shorthand way of dealing with it. The AC
voltage is equal to the RMS value at only two points in
the cycle. Sticking with instantaneous values for everything
AC would complicate things beyond belief.

The values of voltage in your chart were RMS (average) values.
You don't seem to have a problem dealing with RMS values of
voltages and currents. Why do you have a problem with average
power associated with those average RMS values of voltage and
current.

Your view of power and energy is
oversimplified, and it fails when you're pressed to explain what happens
at the interface between the line and the outside world.


What is located at that interface? Anybody is pressed to explain
things when the source impedance is unknown and cannot be measured.

Momentum is conserved in mechanical elastic collisions, but not in
inelastic ones, e.g., when energy is being extracted. I wouldn't begin
to try to apply this to a transmission line, but I see it doesn't bother
you.


Hecht, in "Optics" certainly applies it to EM waves. RF EM waves
differ from light waves only in frequency. Conservation of
momentum is a cornerstone of EM light physics and is included
in the rules of relativity.
--
73, Cecil http://www.qsl.net/w5dxp


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