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Old April 12th 07, 11:35 AM posted to rec.radio.amateur.antenna
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Default Constructive interference in radiowave propagation

On Apr 11, 1:06 pm, Cecil Moore wrote:
Keith Dysart wrote:
So it is settled then. There is no NEED for a forward OR reverse
travelling wave. Differential equations rule.


Yes, it is settled in your own mind. In my mind,
there is certainly a need for forward and reverse
traveling waves without which standing-waves would
not be possible. If you want to deny the existence
of the cause of standing-waves, there is nothing
I can to stop you.


My mistake. But it is difficult to know your position when
you don't indicate clearly that you disagree, so I thought
that with your reply you were agreeing. Apologies.

Well, except for the inability to explain where the "reflected
power" goes in the transmitter. Of course this is not an issue
for carefully selected examples where no "reflected power" reaches
the transmitter. A more general analysis technique would not
require such careful selection of examples.


The more general analysis technique tells us that
the moon is 1000 miles away from the earth. I don't
know how far away the moon is but I know it is not
1000 miles away.


This is a bit of a non sequitur. So what is it that you really
disagree with in the analyses performed by myself and others?

Just for clarity, an example problem that has been previously
analysed is the following:
A generator with a 450 Ohm source impedance drives a 450 Ohm
ideal transmission line terminated in 75 Ohms. What is the
magnitude of the re-reflected wave at the generator?

I think you object to computing the amount of the reverse wave
that is reflected at the generator by using the source impedance.
More specifically you do not agree that the reflection
coefficient at the generator can be derived using
RC = (Zsource - Zline)/(Zsource + Zline).
Also, you do not agree that superposition applies at the source.

Given this, you then do not agree with the computations of the
quantity of the reverse wave that is reflected at the source which
then invalidates any further analysis.

Have I managed to capture the essence of your disagreement with
my and others analyses?

Note that these analyses have been performed without the use of
powers or interference so these side issues are not part of this
question.

....Keith

 
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