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Old May 24th 10, 09:06 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jul 2006
Posts: 143
Default Question about "Another look at reflections" article.

Hi all. I have a doubt about if this text from "Another look at
reflections" reflect the author ideas.

"Laboratory and experimental work often requires holding incident
voltage constant with variation in loading. A constant-voltage source
is usually obtained for this purpose by inserting a pad having 15 to
20 dB attenuation between the generator and the line to absorb the
reflected power, preventing it from reaching the generator where it
would alter the line coupling and cause the generator output voltage
to vary. Because of the absorption of the pad, the generator sees a
nearly perfect match for all load conditions and all reflected power
is lost - but these are laboratory control conditions required to
obtain valid test data."

For example this part = "by inserting a pad having 15 to 20 dB
attenuation between the generator and the line TO ABSORB the reflected
power"

żAbsorb the reflected power or amortiguate the effects of variyng load
impedance?

As I understand it, even without a conjugated match the reflected
power neither returns to the source (Thevenin equivalent source).

I give the following example: If we load a generator directly with a
resistance of 10 ohms, without any transmission line, there are not
traveling waves interfering, therefore there are not stationary waves,
there is only a impedance mismatch affecting the source voltage żOK?.
If then I load it with a line of half wave finished in the same 10
ohms resitance, the generator "will see" a 10 ohms load, and it will
behave identically as it made it with the original "direct" load.
In both cases there is not reflected power that it can return to the
generator...

(I admire Walter's work and this consultation should only be read as a
question, not as a criticism)

Thank you very much in advance.

Miguel Ghezzi LU6ETJ
 
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