Thanks for the very cogent and informative posting, as yours always are.

One thing you said really rang a bell, and made me consider something
I'd never thought much about before. If a coil is radiating
significantly, the Q will of course be necessarily poor due to the
energy "lost" by radiation. Yet this "loss" won't be detrimental to the
antenna performance. Tom Rauch has pointed out that loading inductor
loss is very often insignificant compared to ground loss in a typical HF
mobile system. Maybe the presumed "loss" of some coils is not as bad as
it appears in other antenna applications, either.

Roy Lewallen, W7EL

Ian White, G3SEK wrote:
. . .
This brings us back to the question of practical loading coils, and how
much radiation (and therefore current variation along the length) we can
expect. I haven't ever tried to work it out, but my guess is that a
fairly short "square" coil that has been optimized for high Q is not
going to radiate much, and that we therefore shouldn't expect a large
difference in current between its two ends.
. . .