A few days ago I posted a derviation of the (non-conjugate) formula for
voltage reflection coefficient on a transmission line. It required only
a few assumptions:

1. That the voltage reflection coefficient is the ratio of reverse to
forward voltage.
2. That the voltage at any point along the line, including the ends, is
the sum of the forward and reverse voltages, and that the current is the
sum of forward and reverse currents.
3. That the ratio of forward voltage to forward current, and the ratio
of reverse voltage to reverse current, equal the characteristic
impedance of the transmission line.

Given these assumptions, the derivation is a matter of straightforward
algebra.

For those promoting some other formula for voltage reflection
coefficient: Which of the above assumptions is false? What substitute
assumption is true? And what's *your* dervivation? Remember, we're
talking about transmission lines here, not a one- or two-port analysis
with a "reference impedance" instead of a transmission line, and where
there's no restriction that the total voltage and current are simply the
sum of the forward and reverse components.

Roy Lewallen, W7EL