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Michael Tope wrote:
I am a bit behind on ARRL Handbooks, Richard, but from
what you describe, this is the same figure that appears in my
1992 edition (chapter 38, figure 2). In any case, what is
shown in the figure agrees with my understanding of "broken",
although admittedly when I made my previous post, I was
thinking of the case where the shield is broken on the side of
the loop opposite the feedpoint. For the purposes of this
discussion, however, it doesn't matter whether the break is
at the top (opposite the feed) or at the bottom (adjacent
to the feed). In either case, current induced on the inside
of the shield by current flowing on the center conductor loop
has a continuous back to ground via the outside surface of the
shield. IOW, the gap doesn't suppress the eddy current, rather
it forces it to flow on the outside surface of the shield, thereby
causing the loop to radiate.

Absolutely nothing, neither electic nor magnetic, couplesthrough the
wall of a conductor more than several skin depths thick. This isn't
anything that can be debated, it is simply how it works. It is very
easy to demonstrate, it takes only a few minutes and a minimum of test
equipment.


I don't think we disagree on that point, Tom. Perhaps I should
have chosen my words more carefully. I didn't mean to imply
that gap somehow forces the current on the inside of the shield
to pass through shield. When I said that the gap forces the current
to flow on the outside surface of the shield, I meant that in the
sense that the eddy current flows on the inside of the shield until
it reaches the break in the shield at which point the current flow
wraps around the edge of the shield and onto the outside surface
(thereby reversing direction relative to the direction of the eddy
current on the inside of the shield). The skin effect in effect
separates the shield into two distinct conductors, the inner surface
being one conductor and the outer surface of the shield being the
other. The gap is the circuit node where these two independent
conductors are connected. The eddy current flows out of one
conductor (the inner surface of the shield ) and into the other
conductor (the outer surface of the shield).

73, Mike W4EF.............................................. ...........