On Mar 31, 6:23 am, Cecil Moore wrote:
With as little effort as possible, determine Pfor2 and Pref2.

Given: Pfor1 = 100 watts, Pref1 = zero watts
[(Z02-Z01)/(Z02+Z01)]^2 = 0.5

100w---Z01 ohm line---+---Z02 ohm line---unknown load
Pfor1-- Pfor2--
--Pref1 --Pref2
--
73, Cecil http://www.w5dxp.com

If EITHER line has loss, the problem statement is incomplete, at best.

If the lines are lossless, Pfor2=175W, and Pref2 is obvious.

And it's a REALLY weird way to state the impedances. It looks like
someone was interested in the impedances of the lines after thinking
to make some measurements of VOLTAGE and maybe CURRENT along those
lines and couldn't quite figure out how to get there.

How do we KNOW that Pfor1 is 100 watts and Pref1 is zero?

How do we KNOW that line 1 and line 2 each have UNIFORM impedance?

Simply stating it as a brainteaser doesn't make it relevant to the
problems hams are faced with in line-matching situations. In most
cases, hams ASSUME they know the impedance of the line they are
measuring, whether they realize it or not. That is, they'll use a
bridge to make a measurement, and the bridge is calibrated for use at
a certain impedance (commonly 50 ohms). If the line isn't that
impedance, the measurement will be in error. Just because someone
measured 100W forward and 0W reflected on line 1 doesn't make it so,
and honestly, that's a much more interesting problem to me than this
easy "brainteaser."

Cheers,
Tom