billcalley wrote:
... I understand the concept, but what I don't
quite understand is why the reflected RF energy isn't simply absorbed
by the 50 ohm output of the transmitter after the first reflection?
For the RF to bounce back and forth, wouldn't the transmitter's
impedance have to be very, very high (or low) when the reflected RF
energy hit its output stages? I know I'm missing something vital
here...

Yep, you are missing the "total destructive interference"
happening toward the source caused by a Z0-match. Here's
an article that might help:

http://www.w5dxp.com/energy.htm

A Z0-match eliminates reflected energy from reaching
the source.
--
73, Cecil http://www.w5dxp.com