I performed an interesting shielded loop experiment today with a snap-on
ferrite rfi-choke:

1) When the choke is placed anywhere on the coax feedline the choke has
no affect whatsoever.

2) When the choke is snapped anywhere around the loop-element coax, it
really attenuates the loop signal, and also detunes it. I had to
readjust my tuner's capacitor quite a bit. It also seemed to flatten
out the nice sharp Q. It did not affect the directivity however.
Placement of the choke anywhere on the loop element seemed to produce
the same amount of attenuation - from right over the gap to anywhere
else on the loop.

Unless I misunderstand how ferrite-chokes work, this does seem to
physically point out that the shield is the actual antenna. (This is
what I've been told all along here.) Nobody in their right mind would
place an RFI choke on their transmission line in an effort to reduce
common-mode radiation if it also severely attenuated the wanted signal
right?

Am I on the right track? The correct theory is nice to know, but it is
also great to see it proven physically....

73
Brian