Gene Fuller wrote:

Cecil Moore wrote:
. . .
"... - no wave interferrence and no standing waves can be
present on lumped elements. The problem has been that many
experimenters working with self-resonant helices have
PURSUED THE CONCEPT OF COIL SELF-
CAPACITANCE WITHOUT REALLY UNDERSTANDING
WHERE THE NOTION COMES FROM OR WHY IT WAS
EVER INVOKED BY ENGINEERS. For that, they will have
to go read R.W.P. King's wonderful old book, "Electromagnetic
Engineering, McGraw-Hill, 1945. ... On page 465, the Harvard
Professor points out that, for coils whose *wire length* exceeds
1/6 wavelength, ...'an adequate representation of the reactance
of a coil with a nonuniformly distributed currentr is NOT
POSSIBLE in terms of a coil with a uniform current [a lumped
element inductance] ...' Period. Resonant FIELDS present
surprises to engineers with limited training."

Certainly sounds like he is talking about you, Tom. "Electronic
Engineering" was written before you were born. Why are you
ignorant of the technical facts presented in it?

I have this book. The condition for the quoted result isn't simply that
the length of wire in the coil be adequately long, but also that the
coil be wound loosely enough so that the coupling between turns is poor
enough to allow a particular nonuniform current distribution. It applies
to a "loosely wound helix." The quote is within a section titled
"'Lumped' Constants in Near-zone circuits", which contains a detailed
analysis of just what conditions can cause an inductor to have unequal
input and output currents, but primarily how the currents can be unequal
even in the absence of an external field. In particular, the author
describes an inductor in which the coupling between turns isn't
sufficient to force equal currents at the coil ends. Qualitatively, this
should be pretty obvious: If we begin with a long wire (in terms of
wavelength), the current will vary along its length. As we wind it into
a loose coil, mutual coupling between turns will create inductance and
make the current more uniform, but with a distribution still resembling
that of the straight wire. It's this situation that the quotation
applies to -- an inductor so loosely wound that its current distribution
resembles a straight wire more than an inductance. He does go on to say
that if the winding is tighter but still not ideal, the resulting
non-uniform current, which has a different distribution (greater at the
center than at the ends), can be modeled by means of a lumped self
capacitance. Only if we have perfect coupling between turns (as a toroid
very nearly represents) will we truly have equal currents at input and
output, for the reasons Tom recently explained. This is the idealized
inductance which some of the contributers to this discussion are having
trouble understanding.

The mathematical treatment in King is quite complex. But nowhere does he
mention any traveling, reflected, or standing current, power, or energy
waves, or that an inductance behaves any differently in an antenna than
in a lumped circuit. It simply isn't necessary or relevant to explaining
the operation of either an ideal or non-ideal inductor. Nor does he
dispute the fact that the currents into and out of an ideal inductance
are equal. And of course there's no mention of the mysterious "resonant
fields" which probably do surprise engineers, as does the metaphysics
being promoted here.

Roy Lewallen, W7EL