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Old April 7th 06, 05:42 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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Default Current across the antenna loading coil - from scratch


wrote:
It is the stray capacitance from the inductor to the outside world that
allows any difference in current. Not the standing waves, not the
missing area of antenna.


You are using standing wave current to try to prove your concepts
are valid. If you don't take time to understand standing wave current,
you will never correct those misconceptions.

Standing wave current phase contains no phase information. Therefore,
standing wave current phase cannot be used to measure the phase shift
through a wire or a coil.

The only phase information in a standing wave current is in the
magnitude which roughly follows a cosine function distorted by
the fields in the loading coil.

If the current at the bottom of the coil is 1.0 amps and the current
at the top of the coil is 0.7 amps, the phase shift through the coil
is *roughly* arc-cos(0.7) = ~45 degrees. As Gene Fuller says,
there's no phase information in standing wave current phase.
All the phase information is embedded in the magnitude. That's
easy to see from the I(x,t) = Io*cos(kx)*cos(wt) equation for
standing wave current.

It's also easy to see from: http://www.qsl.net/w5dxp/travstnd.GIF
plotted from EZNEC data.
--
73, Cecil, W5DXP


 
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