Owen Duffy wrote:
"In formula 4-22b of my copy of Terman, the term on the lhs is Irhol
which is the magnitude of the reflection coefficient."

In my copy, 4-22b gives the "absolute value" of the reflection
coefficient (it is embraced with bars) which I believe means the
"absolute value" of a number or a symbol without reference to its
algebraic sign.

(4-22b):
+or- reflection coefficient=
SWR-1 / SWR+1

These formulas, (4-22a) and 4-22b) aren`t just theory. They are
constantly put to use. A derivation which uses the sq rt of the ratio of
refllected power to forward power for the reflection coefficient appears
on page 23 of my Bird Model 43 Directional Thruline Wattmeter Manual.:
SWR = 1+reflection coefficient / 1-reflection coefficient
(Same as 4-22a)

Transmission lines are special because they enforce Zo. That is, in
either direction of travel, when you apply a voltage to the low-loss
line, the current which results is locked in-phase with the applied
voltage. In other words, Zo is a resistance.

Best regards, Richard Harrison, KB5WZI