On Apr 30, 11:26*pm, Jim Kelley wrote:
But when there is a change in the amplitude of the
standing wave in x, and I max is known, then determining the shift in
phase from the equation is a no brainer, Cecil.

Jim,

I'm still reading, trying to understand the various arguments being
put forward!

One thing I'm not clear about is your response to Cecil's point about
phase measurements along a standing wave.

Please correct me if I've got any of this wrong: I'm picturing a half-
wave antenna with a current standing wave in the shape of a (half)
sine wave. My understanding is that if I could observe the current at
a particular point along the antenna its amplitude would vary
sinusoidally with time, and its peak amplitude would be determined by
its distance from the centre of the antenna (and of course by the peak
amplitude of the current at the centre).

If I could observe the current at several points along the antenna
they would all be in-phase, in the sense that they would all reach
peak amplitude at the same time, and cross zero at the same time. The
only thing that would distinguish them would be the peak amplitude.

Cecil seems to be saying that, in a system like the one I've
described, measuring the relative phase of the currents at two points
along the antenna tells you nothing about their (electrical) distance
apart. If I've misinterpreted him, I'm sure cecil will correct me!

Given that the currents all along the antenna are in-phase, Cecil's
point seems so obvious - what am I missing? Or do you actually agree
this point and I've misunderstood your position?

Regards,
Steve