On Feb 28, 3:52*am, "Szczepan Bialek" wrote:
A loop is like a short circuit. What do a Electromagnetic pulse in a loop?
It simply travel *trough the loop and looks like the "reflected with the
opposite polarity ". Why am I wrong and D. Russell is right?

What you are missing is that the loop is an antenna, not a
transmission line. On a transmission line, the currents are
differential, i.e. 180 degrees out of phase and a short-circuit is
possible. At the antenna feedpoint the left differential current takes
a 90 degree turn to the left. The right differential current takes a
90 degree turn to the right. *That puts the antenna currents in
phase*, i.e. in common-mode, so a short circuit on an antenna 40 feet
in the air is not possible. The fields that are 180 degrees out of
phase no longer cancel because of the physical distance between them.

From the feedpoint of the antenna, there is no such thing as waves
launched in opposite directions on the wire *at the same time*. What
you are missing is there is no short-circuit half way around a loop
because there is no impedance discontinuity at that point. Forward
waves continue traveling forward and reflected waves continue to
travel backwards at that point because there is no impedance
discontinuity at that point. It takes an impedance discontinuity to
cause a reflection. Assuming a circular horizontal loop (for the sake
of conceptual simplicity) the only impedance discontinuity is at the
feedpoint.
--
73, Cecil, w5dxp.com