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Old December 6th 08, 12:38 AM posted to rec.radio.amateur.antenna
John Smith John Smith is offline
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First recorded activity by RadioBanter: Nov 2006
Posts: 2,915
Default skin depth (eddy current/Foucault currentO)

Art Unwin wrote:
... So what exactly forces a time varying current
to take an alternate route of travel from the center of a conductor
when the resistance is so low compared to other routes that could be
taken.?
Note : center resistance is lower than that on the surface because
skin depth (opposing eddy currents) cannot form.
Art


I think that question is probably best answered with a question(s) ...

What is a thin element?; What is a thick element? What is the surface
area of the element(s) in question?; what are the power densities
involved?; Does the surface quality of the element cause these
measurements to vary?; In all cases ever recorded, is it ALWAYS the
level you gave, i.e., no anomalies?

I have always thought 1/4 copper tubing with a tenalized SS welding wire
of heavy gage though its center was superior at high power, a lot get by
with much thinner elements. On 10m and lower, I would, generally, use
heavy wall copper pipe of 1/2", or so ... on wifi antennas, I use 1/8
heavy wall brass hobby tubing--I suspect no advantage over thin wall.

I would love access to facilities to investigate this, that lacking, I
would love data I could trust ... what do you find so interesting that
rf might be forced deeper into the surface of elements? I assume from
all my readings and studies that rf prefers the surface--the higher the
freq(s) the more the phenomenon is noted/enforced.

Regards,
JS