Roger wrote:
The resistor in the Thevenin/Norton equivalent source is selected with
some criteria in mind. What I would like to do is to design a Thevenin
source to provide 1v across a 50 ohm transmission line INFINATELY long,
ignoring ohmic resistance. I would like the source resistor to absorb as
much power as the line, so that if power ever returns under reflected
wave conditions, it can all be absorbed by the resistor. I think the
size of such a resistor will be 50 ohms.

If you allow reflected energy to flow through the
source resistor, destructive interference is often
the result and the resistor therefore will not
dissipate the reflected power.

The only way to get the source resistor to dissipate
all of the reflected power is to cause total constructive
interference within the source. That requires all of the
energy from the load side of the system.

When the source rejects reflected energy due to destructive
interference, that energy has no choice except to reverse
direction and flow back toward the load as constructive
interference energy.

Maybe you should reconsider the circulator+load-resistor?
--
73, Cecil http://www.w5dxp.com