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Old April 8th 06, 04:54 AM posted to rec.radio.amateur.antenna
Tom Donaly
 
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Default Current across the antenna loading coil - from scratch

Cecil Moore wrote:
wrote:

So what exactly is the importance of this current YOU are talking
about?



All the diversionary BS trimmed from your posting. Bottom line,
the equation for standing wave current is:

I(x,t) = Io*cos(kx)*cos(wt)

The equation for traveling wave current is:

I(x,t) = Io*cos(ks+wt)

Since you obviously don't comprehend the difference, please
dust off your old math book and take a look.

In case you need a graphics reference for those two equations,
you can find it at:
http://www.qsl.net/w5dxp/travstnd.GIF

You will find the two above currents are virtually opposites
of each other.

In particular, standing wave current phase CANNOT be used to
determine the phase shift through a wire or through a coil
because its phase never changes in a 1/4WL monopole.

I can hardly say it better than Gene Fuller who said:
Regarding the cos(kz)*cos(wt) term in a standing wave:

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.



Please tell us what it is about Gene's posting that you don't
understand.


You know, Cecil, a pulse train also satisfies the wave equation.
Why are you married to sinusoidal waves? Haven't you ever seen
ghosts on a tv picture? What do those Ghosts represent?
73,
Tom Donaly, KA6RUH
 
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