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Old April 3rd 06, 08:15 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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Default Current across the antenna loading coil - from scratch

John Popelish wrote:

Cecil Moore wrote:
That is a false statement and is at the root of the misconceptions.
Standing wave current does not have to be equal.


I assume you are meaning that the RMS current at one physical point must
not equal the RMS current at some other point.


Yes, the RMS value of the standing wave current at the bottom of
the coil doesn't have to bear any relationship to the RMS value
of the standing wave current at the top of the coil.

Aren't you claiming that the coil has transmission line like properties,
in that it takes time for a wave to pass through it?


Yes

Any such device needs two mechanisms for storing energy, one magnetic
(inductive) and one electrical (capacitive). Even free space has both.
If you eliminate either mechanism (or make one of them insignificant, as
would happen to the capacitance if the inductor approaches zero size),
you lose the transmission line like properties as the dominant mechanism.


There is no net charge carried over from cycle to cycle. There is no
net storage of charge even if the steady-state RMS value of the standing
wave current is zero at one end of the coil and 2 amps at the other end.

The problem here is not how a coil works. The problem is how standing
waves work. Forget the coil. Start with a lossless unterminated
transmission line and then step up to a 1/2 wavelength thin wire dipole.

It is obvious that a number of people just don't understand the nature
of a standing wave that doesn't move through a wire along with its
phasor that doesn't rotate relative to the source.
--
73, Cecil http://www.qsl.net/w5dxp