Cecil,

All I can say is why don't you write this magic tale into a technical
article and submit it to your favorite IEEE journal or AIP journal.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

My point is in complete agreement with Tom, W8JI. The only thing that
allows "current taper" is displacement current.


True, but it doesn't happen as W8JI describes.

The distributed capacitance in a coil causes a transmission
line effect. The displacement currents cause delays (phase
shifts) in traveling wave currents. The traveling wave
currents can be considered to have constant magnitude, i.e.
*negligible current taper* in the traveling wave in spite
of the known displacement currents.

The displacement current effect on traveling waves is in
the phase, not the magnitude. Such is illustrated as an
EZNEC result in the left hand graphic at:

http://www.qsl.net/w5dxp/travstnd.GIF

Please note that in spite of the distributed capacitance,
the magnitude is fixed and flat, i.e. no taper. The displacement
currents cause phase shift delays in traveling waves but has
virtually no effect on the magnitude of the traveling wave.

The distributed capacitance is the same in the transmission
line whether a single traveling wave is present or standing
waves present. So displacement currents don't necessarily
result in current taper. How do you explain that one?

Now take a look at the right hand graph involving standing
wave current. The *phase is fixed and unchanging*. The magnitude
of the standing wave current is *tapered as a cosine function
of distance from the source*. Displacement current indeed does
cause this effect but it is a transmission line effect of
superposition of forward and reflected waves, not the effect
of some imagined sideways third path for current to earth ground.