[TowerTalk] Mismatch loss and tuners
DavidC
davidc@bit-net.com
Fri, 21 Aug 1998 18:46:43 -0400
> the 7.41 dB of REFLECTED POWER IS NOT LOST
> POWER, but circulates in the line.
> 73, Walt Maxwell, W2DU
This is an interesting theory on paper, though it doesn't "feel" right ...
I need some help understanding it. It is clear that nothing is lost
(conservation of energy), whether it remains RF energy or is converted to
heat, but I thought the real question is what is radiated by the antenna
alone.
If I have a pipe with a funnel on the end (narrow side out) that I am
trying to force some water through under great pressure, the backpressure
causes the water to find other ways to escape ... why is it not likely that
considerable quantities of signal are leaching out all over the place
turning sections of the feedline and the rest of the system prior to the
antenna into radiators and dummy loads due to the high "resistance" to
radiation present at the antenna feedpoint ... has the actual radiation of
the "7.41 dB of reflected power" out of the antenna been actually measured
with field strength meters ... or are we trusting theory alone?
I do understand that we have stipulated a lossless feed system and in that
non-reality circumstance nothing but the inherent loss of the tuner (isn't
this loss repeated at every cycle? and how many cycles are there?) causes
any loss of signal. Theory says that this perpetual-motion machine will
eventually squeeze most of the signal through the unfortunate funnel that
is the antenna ...
Perhaps I am becoming a "show me the money" cynic ... blame Bill ... :-)
What about the real world system?
Do I not understand correctly that the feedline and other elements
(connectors, switches, baluns) all represent cumulative loss and
undesirable radiation? Does this loss not reoccur every single time that
the energy runs up and down the line between antenna feedpoint and tuner?
Is there really all that much power left after many cycles? (sort of like
fees assessed against an old forgotten passbook bank account over time)
Does profound real world loss occur or not occur when there a 20:1
choke-point at the antenna feedpoint? Help!
73, DavidC AA1FA
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