On Dec 12, 5:52 pm, Cecil Moore wrote:
Roy Lewallen wrote:
-- IF there's a phase change at the impedance discontinuity (which I
assume means the black box terminals), it's the same for all four (your
three and my one) black boxes.

To see exactly how wrong that statement really is let's
take a look at two of the cases.

(1) with a -j567 ohm impedor (capacitor) connected inside
the black box to the existing 43.4 degrees of 600 ohm
line external to the black box.

(2) with 46.6 degrees of 600 ohm line connected to the
existing 43.4 degrees of 600 ohm line external to the
black box.

The reflection coefficient for (1) at the black box
terminals is 1.0 at -93 degrees, i.e. 100% reflection
at that point with an accompanying phase angle shift.

The reflection coefficient for (2) at the black box
terminals is 0 at 0 degrees, i.e. no reflections at
that point and no accompanying phase angle shift at
that point.

To assert that the phase change at the black box
terminals is the same in both of those cases is
ridiculous. In case (1) it is 93 degrees. In case (2)
it is zero degrees.

So, when you are presented with 43.6 degrees of
600 ohm line connected to a black box (about
which you know nothing of the internals) which
provides an impedance -j567, do you answer the
question: What is the impedance at the input
of the 600 ohm line? Or do you refuse, because
you do not know what phase change is
occuring at the terminals?

....Keith