John Popelish wrote:
Cecil Moore wrote:
Compared to zero amps of standing wave current when the forward current
phasor and the reflected current phasor are 180 degrees out of phase,
just how much effect can capacitance have?

A standing wave voltage passes exactly as much (AC RMS) current through
a capacitance as a traveling wave voltage does.

But the two waves are different as can be seen from their
equations. A traveling wave transfers net energy along a
transmission line or antenna wire. A standing wave transfers
zero net energy along a transmission line or antenna wire.

From "Fields and Waves in Modern Radio", by Ramo & Whinnery,
2nd edition, page 43: "The total energy in any length of line
a multiple of a quarterwavelength long is constant, merely
interchanging between energy in the electric field of the
voltages and energy in the magnetic field of the currents."

Hecht says it best in "Optics" concerning standing waves:

"The composite disturbance is then:

E = Eo[sin(kx+wt) + sin(kx-wt)]

Applying the identity:

sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B)

yields:

E(x,t) = 2*Eo*sin(kx)*cos(wt)"

"This is the equation for a STANDING or STATIONARY WAVE, as opposed
to a traveling wave. Its profile does not move through space; it is
clearly not of the form Func(x +/- vt)."

[Standing wave phase] "doesn't rotate at all, and the resultant
wave it represents doesn't progress through space - its a standing
wave."

Speaking of "... net transfer of energy, for the pure standing
wave there is none."
--
73, Cecil http://www.qsl.net/w5dxp