Bob Agnew wrote:
So how does a 1/2WL piece of transmission line driving a
50 ohm load wind up with the voltage and current in phase
no matter what the SWR?

If the characteristic impedance of the transmission line is 50 ohms, then
there are no reflections; furthermore the current and voltage are in phase
at every point along the line, There are no standing waves in this case.

But I didn't say Z0 equals 50 ohms. What if Z0 equals 75 ohms?
300 ohms? 450 ohms? 600 ohms? Assuming lossless lines, those
Z0's will all result in 50 ohms looking into them when they
are 1/2WL long. Thus the voltage and current will be in phase
for 1/2WL no matter what the characteristic impedance and no
matter what the SWR.
--
73, Cecil http://www.qsl.net/w5dxp