Ian White, G3SEK wrote:



Yes, that is a true observation, just as true as the one I made... so
now you have *two* different things to explain!

The so-called SWR meter is a steady-state instrument, so it always makes
sense to use that quicker, easier way of thinking. Since you're the one
who chooses to think of this particular situation in terms of multiple
reflections, any difficulties you encounter are entirely yours.

If you ever see a conflict between two different theories that explain
the same observed facts, then there's an error somewhere. If the
multiple-reflection theory is extrapolated to infinite time, so that it
calculates results for the steady state, it *must* give identical
results to the steady-state theory. But whenever the steady-state theory
can be used, it will always get you there much more quickly.

However, when you have finally done it your way, and accounted correctly
for all the reflections and re-reflections, we can predict the outcome
with complete confidence:

1. If you sum the successive reflections correctly to infinity, and
calculate the V/I ratio and phase at the station end of the line, then
the final result will be identical to the impedance given by the
steady-state transmission-line theory. It has to be, because that single
value is the reality.

2. Somewhere in your calculations, any value that you assume for the RF
source impedance is going to cancel right out of your calculations. The
correct mathematical result *must* be independent of that value -
because, again, that's the reality.



This is correct. If you divide the formula for voltage, at any point on
a transmission line, by the formula for current, the generator impedance
cancels.
73,
Tom Donaly, KA6RUH