On Tue, 23 May 2006 15:31:13 -0700, Roy Lewallen
wrote:

Richard Harrison wrote:
Roy, W7EL wrote:
"It`s a myth that there`s no magnetic field in the space between a
capacitor`s plates."

Maxwell`s great speculation was that "displacement current", as between
a capacitor`s plates, produced magnetic flux as does conduction current.
His speculation is now proved.

Yes. So how does a capacitor between two inductors constitute "E-field
transfer with zero magnetic coupling" as you stated?

Hi All,

Really, this contretemps seems to be over a matter of scale and
application.

Ramo, Whinnery, and Van Duzer make clear distinctions between mutual
couplings and radiative couplings. Most of the discussion in this and
related threads appear to discard these distinctions.

Richard's application of screened air linked couplers and using the
illustration of power transformers is found in "Fields and Waves..."
by these authors:
"Where there is a component of the electric field in phase with
the current, the integral of the electric field cannot be
considered either as a pure "capacitive" or "inductive" voltage
drop since there will be real energy transfer (radiation) from
these terms."
Richard's applications and illustrations do not push this boundary. In
fact, Ramo et. al distinctly offer the case of "electrostatic
shielding" and clearly support the separation of magnetic and electric
flux (fields). And so as to anticipate the conundrum of the "static"
in electrostatic, the authors show no issue. However, they do provide
a rational warning:
"It often happens that electrodes, although grounded
for direct current, may be effectively insulated or floating
at radio frequencies because of impedance in the grounding
leads. In such cases the new electrodes do not accomplish
their shielding purposes but may in fact increase capacitive
coupling."

Insofar as Yuri's complaint, it is an ego trip that wholly ignores the
scales of wavelength, the application of materials, the nature of
balance, and the misapplication of mutual coupling to explain far
field effects. In short, he has been bitten by the "lumped vs.
distributed" distinction once again. The only saving grace of his
argument may be found in that there are two forms of the "shielded
dipole" where one supports Tom's claim, and the other support's
Yuri's.

Unfortunately, as correct as Richard's examples are, they too are
misapplied to the "shielded dipole." The "shielded dipole" may be
small in relation to wavelength, but its response mechanism is NOT
found by using mutual coupling math, but rather through radiation
math.

73's
Richard Clark, KB7QHC