On Mar 29, 7:17 pm, Cecil Moore wrote:
The answer is subtle. Consider the following lossless example.

XMTR--x--1WL 450 ohm line--y--1WL 450 ohm line--50 ohm load

The SWR is 9:1 everywhere on the 450 ohm line.
(Vf+Vr)/(If+Ir) = 50 ohms at points x and y. There are reflections
to the left of y but no reflections to the left of x. Why?

The physical rho
at point y is zero. The physical rho at point x is 0.8. That's
the difference. Reflections occur only at physical impedance
discontinuities.

Certainly true. To be somewhat more complete there is another
rho at x. You have correctly computed rho from the generator
to the line, but there is also a rho from the line to the
generator: -0.8. This can handily be used to compute the
magnitude of the reflected signal that is re-reflected
towards the load. And when dealing with transients, will
permit you to compute the magnitude of the ghosts, of
which there are an infinite number for each change in
the signal, though of declining magnitude. In a sense,
the ghosts show how the system settles to its
'steady-state'.

....Keith