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Old July 8th 15, 11:47 PM posted to rec.radio.amateur.antenna
Ralph Mowery Ralph Mowery is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 702
Default An antenna question--43 ft vertical


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Ralph Mowery wrote:


Can you show any place where the SWR definition mentions the Source
impedance ?


I have several times now, but once again:

SWR = (1 + |r|)/(1 - |r|)

Where r = reflection coefficient.

r = (Zl - Zo)/(Zl + Zo)

Where Zl = complex load impedance and Zo = complex source impedance.

https://en.wikipedia.org/wiki/Reflection_coefficient

http://www.antenna-theory.com/tutori...nsmission3.php


YOu have just proven my point. Read carefully from your refernce to
Wikipedia :

"The reflection coefficient of a load is determined by its impedance and
the impedance toward the source."

Notice it says TOWARD and not THE SOURCE.

From the second referaence notice that it says load impedance and impedance
of the transmission line. Nothing mentions the source at all:

"The reflection coefficient is usually denoted by the symbol gamma. Note
that the magnitude of the reflection coefficient does not depend on the
length of the line, only the load impedance and the impedance of the
transmission line. Also, note that if ZL=Z0, then the line is "matched". In
this case, there is no mismatch loss and all power is transferred to the
load."