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Old December 2nd 07, 08:49 PM posted to rec.radio.amateur.antenna
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Default Tom's experiment

Owen Duffy wrote:
Tom did not describe any form of directional coupler that would
effectively isolate and measure the forward and reflected waves at each
of the measurement points. Such a thing would be a considerable challenge
since Zo of the equivalent line varies with frequency and he sweeps from
0.3 to 30MHz in his measurement.


Something I observed and reported more than 2 years ago
in a heated exchange over on QRZ.com.

If a simple current probe was used to sample the magnitude and phase of
the current at each end of the coil, the samples are each of the sum of
the forward and reflected current components at each point.


Something I observed and reported.

It is the nature of a low loss transmission line less than an electrical
quarter wave and terminated in a short circuit, that the phase of the
(net) current at all points on the line is almost uniform.


Something I observed and reported. I got "ploinked" by W7EL
for that observation, among others - like energy actually
existing in reflected waves. Wonder if W7EL will now "ploink"
you?

Is it any surprise that Tom's measurement of delay indicates an apparent
phase change much smaller than the value of Beta*CoilLength?


No, but it is a surprise that Tom attempts to disguise and
rationalize that measured phase change as the *delay* through
a 100 turn coil. If his measurements were correct, I could
speed up my computer bus by installing coils in series with
the data lines. :-)
--
73, Cecil http://www.w5dxp.com
 
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