"Cecil Moore" wrote in message
...
Steve Nosko wrote:
I won't get
insulting (nudge, nudge, wink, wink), but I have this bone in my head
which
makes me WANT to say "I know I'm right, I tried to help you understand
so
you go prove it to yourself." without sounding insulting...

Well, Steve, maybe you can tell us exactly what happens at the Z0-match
point in the following system. What changes the direction and momentum
of the reflected power wave from the load?

100W XMTR---50 ohm coax---x---1/2 WL 450 ohm ladder-line---50 ohm load

Well, Cecil... First, I don't know what point you refer to as "Z0-match
point".

If it is the "---x---", I proceed...
For the way you pose the problem (with no other constraints), the Z @ "x"
seen toward the load is 50 ohms, so all is happy in the universe. The 100W
enters the ladder line and exits at the "50 ohm load". I'm obviously
assuming I don't have balanced-to-unbalanced-problems and I know the good
'ole G5RV does this.
So I'd have to ask you just what point are you examining? Is it the
use of balanced T-Line as a matching transformer in an unbalanced system, or
something else?
I think this setup is a sub-optimal way to do it...but Hey! if it
works, use it. Manu suboptimal things are used all the time.


I don't know from "momentum" of power. If you asking what is going on
within the section of ladder line... The easy explanation is that the waves
act such that the two ends look line 50 ohms (OH YES, this DOES assume the
TX has a 50 ohm Zout... I think). I'd have to study the detail for a while
to come up with my mental model and be able to put it into words. I know
that the subject of "which way is power flowing" and "what happens at the
source" and "how many reflections really occur" are big topics here. I
don't get into these discussions because 1) it's been a long time since I
studied it and 2) the path and nitty-gritty detail has faded into the far
recesses of my mind and I would surely stumble around for a proper answer.

I am currently teaching a class in communications which will get into
T-lines later. If I need to get this deeply into the subject, perhaps I'll
come back and post my take on it.
--
Steve N, K,9;d, c. i My email has no u's.