Dan Finn wrote:
I need to find a reference that
has the derivation showing that rho**2 = power lost.

If the source is a signal generator equipped with a
circulator and load resistor, that would be the case.

For more ordinary sources, there are many variables.
It depends upon the phase angle between the forward
wave and reflected wave at the source and upon the
source impedance seen by the reflected wave.
--
73, Cecil http://www.w5dxp.com