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Old May 26th 10, 02:45 AM posted to rec.radio.amateur.antenna
Keith Dysart[_2_] Keith Dysart[_2_] is offline
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First recorded activity by RadioBanter: May 2007
Posts: 492
Default W2DU's Reflections III is now available from CQ Communications,Inc.

On May 25, 8:45*am, Cecil Moore wrote:
On May 25, 5:29*am, Keith Dysart wrote:

It does not seem possible for a system to be non-linear at one end and
turn in to a linear system at some other point.


Well, consider the following two systems. Z01 is 50 ohms and Z02 is
300 ohms. The two systems are identical except for the circuits hidden
inside the two identical source black boxes. Both sources are
supplying a 100v sine wave to the system.

Source1----Z01----+----1/4WL Z02----1800 ohm

Source2----Z01----+----1/4WL Z02----1800 ohm

Every passive voltage, current, power, and impedance measurement is
identical in both systems. As far as we can passively measure, both
systems are identical and linear. The only thing we don't know is what
is inside the two source boxes..

Inside the Source1 box is a linear ideal 50 ohm Thevenin equivalent
source delivering an ideal 100v sine wave. Inside the Source2 box is a
non-linear class-C amplifier filtered to provide an ideal 100v sine
wave.

Without changing the system conditions, can one make a passive
measurement to determine which system is conjugately matched and which
one is not conjugately matched? If one cannot tell the difference, are
they both conjugately matched, or both not conjugately matched, or
what?

Here's my take. A 50 ohm Z0-match exists in both systems and all
conditions are identical on the load side of that Z0-match. In
particular, at any point in the system on the load side of the Z0-
match, the impedance looking in one direction is the conjugate of the
impedance looking in the other direction. That is a characteristic of
a conjugate match. So are both systems conjugately matched between the
Z0-match and the load? If it walks and quacks like a duck ...


Methinks you have so constrained the experiment as to make it
unsolvable.
But let us test that.

Consider a Source3, much like Source1: linear, ideal, but 100 ohms
output impedance. It is connected to the same load you specify for
Source1 and Source2 and adjusted to drive 100 volts in to the 50
ohm Z01 line.

You are presented with the circuits using Source1 and Source3.

We know that Source1 and Source3 can not both be conjugately
matched.

"Without changing the system conditions, can one make a passive
measurement to determine which system is conjugately matched and which
one is not conjugately matched? If one cannot tell the difference, are
they both conjugately matched, or both not conjugately matched, or
what?"

....Keith