Joel, think of it this way... Consider the "shielded loop" in which
the gap is at the top, and the left side is a piece of coax. The
outer of the coax is just the loop "shield" on the left side. The
coax center conductor connects to the right side of the loop "shield"
at the top, across the gap. So the current in the coax center
conductor is just the same as in the shield right side. In other
words, for a loop which is very small compared with a wavelength (at
least), the current in the center conductor is the same as the current
on the outside of the left half of the shield, and in phase with it.
In other words, it's the same as in an unshielded loop. I don't see
any phase reversal there.

Or consider it this way: the loop encloses essentially the same
time-varying magnetic field, whether you look at the loop formed by
the "shield" or the loop formed by the wires inside the "shield."

Cheers,
Tom

"Joel Kolstad" wrote in message ...
"Richard Harrison" wrote in message
...
Yes, a phase reversal is produced by the change of current direction
between the outside and inside surfaces of the loop shield. But carry
your logic a bit further. There is a second phase reversal provided by
the inductive coupling between the inner surface of the loop shield and
the wire loop inside the shield.

Sure, of course... but there's also a (single) phase reversal in the
unshielded loop. Hence the overall difference between the shielded and
unshielded loop is still a single phase reversal. Or do you disagree?

---Joel