If you put the perfect voltage source and the source resistor into a box
and label it "Source", you have a Source whose impedance perfectly
matches the transmission line. It's a Z0-matched system.

The source impedance of my circuit is as simple as it can get. If you
can't explain how it works, it reveals a deficiency of your theory; I
can easily calculate the voltage, current, and power in any component at
any moment of time. Without requiring bouncing waves of average power.
Or a circulator.

Roy Lewallen, W7EL

Cecil Moore wrote:
Roy Lewallen wrote:

Isn't it possible to explain what happens to the "reverse power"
without a circulator?


It is certainly possible in a Z0-matched system where
zero reflected energy reaches the source and the source
is feeding its designed-for load. If no reflected energy
reaches the source, the source impedance doesn't matter,
except for efficiency, which doesn't affect the rest of
the system. A one ohm source providing 100v to a 50 ohm
load and a one megohm source providing 100v to a 50 ohm
load will result in identical external conditions when
driving a 50 ohm load.

The picture is not as clear when reflected current and
voltage are allowed to flow into the source. We usually
don't know what the source impedance is and that
certainly handicaps any analysis. Modern designers simply
resort to protection circuitry and don't worry about
the energy analysis. We do know that reflections reaching
the source are not benign.

Roy Lewallen wrote:
If you put the perfect voltage source and the source resistor into a box
and label it "Source", you have a Source whose impedance perfectly
matches the transmission line. It's a Z0-matched system.

Sorry, Roy, a 50 ohm source driving a 200 ohm load is NOT a
Z0-matched system by any stretch of the imagination. From the
ARRL Antenna Book: "The Z0 mismatch (at the load) creates a
reflection having a magnitude of rho = (ZL-Z0)/(ZL+Z0)
causing a reflection loss rho^2 that is referred back along
the line to the generator. This in tern causes the generator to
see the same magnitude of Z0 mismatch at the line input."

This exactly describes your example which has a 50 ohm Z0
mismatch (and a 200 ohm Z0 match). The mismatch is easy to
see in the following:

50 ohm source--1WL 200 ohm line--+--1/2WL 50 ohm line--200 ohm load

Point '+' is a Z0-match to 200 ohms. A Z0-match to 50 ohms
doesn't exist anywhere.

The source impedance of my circuit is as simple as it can get. If you
can't explain how it works, it reveals a deficiency of your theory;

You assume I don't know how it works because you don't even know
what a Z0-match is???????? How very typical of you.
--
73, Cecil http://www.qsl.net/w5dxp


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Roy Lewallen wrote:
If you put the perfect voltage source and the source resistor into a box
and label it "Source", you have a Source whose impedance perfectly
matches the transmission line. It's a Z0-matched system.

This is exactly like the ham who puts up a random length dipole,
feeds it through a 9:1 balun using 450 ohm ladder-line, and
declares that he has a Z0-match.

50 ohm
100v
source--+--1/2WL 50 ohm feedline--+--200 ohm load

Measuring the 50 ohm SWR at your source output yields 4:1.
Measuring the 200 ohm SWR at your source output yields 1:1.
It is *NOT* Z0-matched to the 50 ohms inside your source.

In a lossless system, a Z0-match to the source impedance
would imply a conjugate match and maximum power transfer.
Your example obviously does not transfer maximum power.
--
73, Cecil http://www.qsl.net/w5dxp

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