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Old April 2nd 06, 09:20 PM posted to rec.radio.amateur.antenna
Tom Donaly
 
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Default Coils and Transmission Lines.

Cecil Moore wrote:
Tom Donaly wrote:

Hecht forgot to put the phase difference in his formula.
It's no wonder there's no phase information in your
standing waves, Cecil, Hecht left it out.



You are mistaken. If Hecht left it out then so did Gene Fuller.
I suggest you listen to Gene when he says: Regarding the
cos(kz)*cos(wt) terms in the standing wave equation:

Gene Fuller, W4SZ wrote:

In a standing wave antenna problem, such as the one you describe,
there is no remaining phase information. Any specific phase
characteristics of the traveling waves died out when the startup
transients died out.

Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen
again.

The only "phase" remaining is the cos (kz) term, which is really an
amplitude description, not a phase.



Not only
that, but where did he get the idea that it was sin(kx) instead
of cos(kx). I understand Hecht is a good old boy, but I'd like to
see his derivations.



Apparently, you are ignorant of the difference in conventions between
optics and RF engineering. In optics, there is no current so there is
no current changing phase at an open circuit. In optics, the M-field
changes directions but not phase. In RF engineering, a change in
direction of the H-field is considered to be a 180 degree phase shift.
Both conventions are correct as long as one understands them. Your
strange statement about Hecht above just proves your ignorance.


Whatever. I'd still like to see his derivations. In your case,
you're using the wrong equation anyway. What you really want is
Beta*l, or the radian length of your transmission line. You can
get that if you know, or can measure the usual parameters in the
transmission line impedance equation, using that equation to solve
for Beta*l. That won't prove your theory because you still haven't
shown that any one transmission line model is unique in terms of
substituting for your coil, but at least it'll give you something
to do.
73,
Tom Donaly, KA6RUH
 
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