Walter Maxwell wrote in
:

....
voltage and current values of rho at the matching point which produces
either a virtual short or a virtual open circuit that causes the
re-reflection. I have shown this to be true in my QEX article of
....

Walt,

I am talking about the steady state.

I see discussion about this need for total re-reflection at the source,
and some even describing the function of an ATU as a "total re-
reflector", and it makes me wonder why we are grappling with re-
reflection at the source end of the line in the steady state.

My understanding is that:
1. The ratio of elecric field to magnetic field per unit length (or V/I)
in an infinite transmission line is constrained by the geometry of the
line and the permeability and permittivity of the components carrying the
two fields. That ratio is expressed as Zo.
2. If a wave with V/I=Zo reaches the end of the line, and the load does
not permit V/I to be Zo (ie a mismatch), a reflected wave is launched,
and it is of magnitude and phase such that (Vf+Vr)/If-Ir)=Zl (all complex
values).

In the steady state, after all has settled (ie converged), the
transmission line reaches an equilibrium where the source V/I
characteristic is consistent with (Vf+Vr)/If-Ir) at the input end of the
line.

Why is it necessary to complicate the analysis with tracking multiple re-
reflections, potentially an infinite number of reflections of diminishing
significance, an analysis that converges in the limit on the answer given
by the solution of the source V/I characteristic and (Vf+Vr)/If-Ir) at
the input end of the line (which is the equivalent input impedance). Note
that (Vf+Vr)/If-Ir) at the input end of the line is determined solely by
the tranmission line propagation constant, length, Zo and the far end
load impedance, for avoidance of doubt, source impedance is not
relevant.

Such an approach does not require invention of virtual re-reflectors or
virtual s/c or o/c, or ATUs or pi couplers with virtual properties.

Owen

PS: Before someone brings up TV ghosts, they are not steady state
phenomena. If significant distortion of modulation is caused by
reflections, then clearly the scenario is not sufficiently steady state
to allow steady state analysis.