Cecil, W5DXP wrote:
"A flat system is conjugately matched, i.e. you see 50+j0 in one
direction and 50-j0 in the other direction."

Let`s simplify Cecil`s example. 50+j0 and 50-j0 can both be expressed as
50 ohms resistive. In other words they are the same.

A matched 50-ohm transmission line under maximum power transfer
conditions also has a 50-ohm source.

Conjugate matching is equivalent to maximum power transfer.

I agree with Cecil that: "A flat system is conjugately matched, i.e. you
see 50+j0 in one direction and 50-j0 in the other direction."

No matter where you slice the transmission line you see 50 ohms
resistive (volts and amps are in-phase) looking in either direction.
Nothing amiss except the word "conjugate" is superfluous in the special
case where the system is free from reactance.

Best regards, Richard Harrison, KB5WZI