Richard Harrison wrote:
This says that in the impossible case of zero radiation and zero loss,
the coil current is the same at both ends of the coil.

This would be true for traveling-wave antennas. But in a standing-wave
antenna, the net current is the sum of the forward current and the
reflected current. Even if the coil had zero radiation and zero loss,
a real-world coil would have a delay through the coil. That delay
changes the relative phase between the forward and reflected currents
making the net current different at each end of the coil even for a
coil with zero radiation and zero loss. The forward currents would be
equal into and out of the coil. The reflected currents would be equal
into and out of the coil. But their phasor sum would differ due to
phasing.

Assume the forward current and reflected current are in phase at zero
degrees at the feedpoint. The net current is simply the algebraic sum of
those two values. But 45 degrees out from the feedpoint, the forward
current is at 45 degrees and less than at the feedpoint. The reflected
current is at -45 degrees and greater than at the feedpoint and the
sum of the two currents is the sum of two phasor currents 90 degrees
apart. At 90 degrees, at the end of the antenna, the forward current
and reflected current are equal and phasor sum to zero.
--
73, Cecil http://www.qsl.net/w5dxp



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