Walter Maxwell wrote:
No Cecil, Johnson didn't screw up. Incidentally, the equation in question is his
Eq. 4.23, derived on Pages 98 and 99, and displayed on Page 100. Steve screwed
up because, as I've been repeating, he misinterpreted the equation to determine
the forward wave instead of the standing wave.

On page 99, in between equations 4.22 and 4.23 is an equation presented by
Johnson that is close to Steve's equation to which you are objecting.

From all of your statements so far, it appears you may have misunderstood what
the forward wave really is. Here's a clue. When a tuner is properly adjusted in
matching a 50-ohm line to a 150 + j0 resistance and the output voltage of the
source is 70.71 v. the forward voltage is 70.71 x 1.1547 = 81.65 v. Do you
recognize it or know where the 1.1547 came from ? Steve doesn't have a clue.

The forward voltage wave equals s21(a1)+s22(a2) which is virtually the same
as V1+V2 because V1/[SQRT(Z0)] + V2/[SQRT(Z0)] = s21(a1) + s22(a2). It's the
old one-to-one correspondence rule.

As I said before, Walt, the 1WL section of 50 ohm line in Steve's example
is *completely irrelevant* to the discussion. Steve only included that line
so the forward/reflected power could be measured and the impedance reproduced.
As long as you allow that 1WL of 50 ohm line to enter into your thinking and
calculations, you will never understand what he was trying to say. Please remove
the 1WL of 50 ohm line and please re-think your position. All the conditions
discussed by Steve occur at the *MATCH POINT* which, I think you will agree,
is NOT on the 50 ohm line.
--
73, Cecil http://www.qsl.net/w5dxp



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