On Sat, 04 Oct 2003 18:00:39 -0700, Roy Lewallen wrote:

Whenever you're dealing with current, you have to pay attention to the
definition of positive direction. If you define the positive direction
of forward current as being toward the load and of reflected current
toward the source, then Vf is in phase with If and Vr is in phase with
Ir. I suspect that a similar caution needs to be heeded when dealing
with optics.

Roy Lewallen, W7EL

Well, Roy, if what you say above is true then why does the phase of reflected
voltage change 180 degrees and reflected current does not change when the
forward waves encounter a perfect short-circuit termination?

And on the other hand, why does the phase of reflected current change 180
degrees and reflected voltage does not change when the forward waves encounter a
perfect open-circuit termination?

How then can the reflected voltage and current be other than 180 degrees
regardless of the load?

If what you say is true then my explanation in Reflections concerning the
establishment of the standing wave must be all wrong. Is this what you're
saying?

Walt, W2DU

Cecil Moore wrote:
Walter Maxwell wrote:

Sorry, Cecil, the phase between reflected voltage and current is
always 180
degrees, not zero.


Yep, I know better, I just mis-spoke. Did you know that there is no
such convention for light? It's Kirchhoff's current convention that
dictates a 180 degree phase between reflected voltage and reflected
current. EM light doesn't follow Kirchhoff's convention.

For EM light, there is no phase shift in the reflection if the index
of refraction is higher. If the index of refraction is lower, there
is a 180 degree phase shift in both E and H fields.