Ian White GM3SEK wrote:
In this particular case, the impedance at the terminals of the black box
is the only *necessary* information to solve the transmission-line
problem (in the steady state, at one frequency). It is not necessary to
know how that impedance was created.

Black boxes have their function but I doubt that any proponent
of black boxes will admit that the function proposed here is
to obscure technical facts because those technical facts are
distasteful to some people.

Ian, the entire problem (as stated previously by me) is to
ascertain the phase shift at the impedance discontinuity
between Vfor1 in the 600 ohm line and Vfor2 in the 100 ohm
line at point '+' in the following example. That is the
problem as stated. It's a straight forward problem - no
black box necessary.

--43.4 deg 600 ohm line--+--10 deg 100 ohm line--open
Vfor1--|--Vfor2

Assuming the voltage incident upon the open end of the stub
is 100 volts at 0 degrees, I calculate the following voltages
at point '+'.

Vfor2 = 100 volts at -10 degrees

Vfor1 = 143.33 volts at -46.6 degrees

The phase shift between Vfor1 and Vfor2 is 36.6 degrees.

You should be able to prove or disprove those values. In
fact, you seem to be frothing at the mouth wanting to
disprove them. Well, go ahead and prove me wrong (if you
can).

Instead of performing the calculations to disprove my figures,
you attempt to sweep part of the problem under the rug by
putting everything from point '+' to the end of the stub in
a black box thus making the stated problem impossible to solve.
I'm sorry, but that is an unethical diversion away from the
stated problem.

I have already stated that no matter what is in the black box,
if the impedance or impedor is -j567 then the conditions external
to the black box are identical. But that diversion has nothing
to do with solving the original problem.

Why are you afraid to solve the problem as stated? I am going
to keep repeating this posting until someone provides a solution
to the original problem.

My voltage calculations above are either right or wrong. If
they are wrong, as you suggest, please prove it. If they are
right, I don't blame you for trying your best to suppress the
technical facts by hiding things in a black box but now the
whole world is aware of your attempted suppression of
technical facts, not a good reputation to have for a technical
editor.
--
73, Cecil http://www.w5dxp.com