My understanding is that the phase of the forward and reflected waves
varies along the transmission line. One 'rotates clockwise' the other
'rotates counterclockwise'. In the case of 'perfect reflection', a
mathematical study condition, the sum of these two waves varies along
the transmission line. The resultant sum produces the minimum and
maximum voltage we observe in a slotted line. It is to be noted that the
phase shifts at the all half wave points from the load, by convention,
rotate from the 'positive' two quadrants to the negative two quadrants.
Therefore, a polarity change exists.

Is this the 180 degree phase shift being discussed?

Deacon Dave, W1MCE
+ + +

SNIP

At no time do these phases suddenly reverse direction.


Aha, so you disagree with Kraus and apparently don't understand the
thin wire analysis of standing waves in his book.

If you choose to call the switch from current flow in the positive
direction to the negative direction a 180 degree phase shift, so be it.


SNIP