Richard Harrison wrote:
Cecil, W5DXP wrote:
"Assuming the source signal is a pure sine wave, if the standing wave
current "isn`t in general sinusoidally shaped (as Roy said)", then the
antenna would have to be introducing harmonic radiation that doesn`t
exist in the source signal."
. . .

Either Cecil is misquoting me, or Richard is misquoting Cecil.

Cecil calls the total current the "standing wave current". I never said
that the standing wave current isn't sinusoidally shaped. I said that
the *envelope* of the standing wave -- that is, a graph of the magnitude
of the current on a transmission line as a function of position along
the line -- is not sinusoidally shaped except in the special case of a
complete reflection. This isn't a personal theory, but a very well
established fact which can easily be derived from fundamental equations.
(Or it can even be found clearly stated in texts for those unable to
understand the derivation.) On antennas, the current distribution
(magnitude of current vs position) is generally not sinusoidal either,
although it's approximately so on thin wire antennas.

Assuming that the transmission line is driven with a pure sine wave, the
forward, reverse, and total currents as a function of *time* will be
sinusoidal and consequently no harmonics will be generated. (I'm of
course neglecting nonlinear effects which might occur in a real
transmission line or antenna such as magnetic conductors or nonlinear
dielectrics. But in practical terms these will be virtually unmeasurable
with ordinary coax or twinlead and amateur power levels.)

It's hard to determine whether Cecil's sustained confusion between a
time waveform and a graph of amplitude vs distance is intentional or if
the concepts are really mixed up for him. It has, in either case,
provided a convenient diversion from his basic strange theories at the
time it was getting particularly hard for him to continue supporting them.

Roy Lewallen, W7EL