>All transmission lines have a characteristic or surge impedance
>value. But - since the system impedance is set by the termination,
>VSWR can appear on any line. When you have VSWR, the rf on
>the line will have voltage and current peaks and nulls.
Correct.
>Depending on where you put your meter in the line, you can have
>high swr or low swr.
No. Assuming the line is lossless, the SWR is constant along the entire
length of the line. And, a good SWR meter will measure this constant SWR no
matter where it is placed in the line. What does vary along the length of
line is the impedance (real plus reactive) you would measure looking back
toward the load. This is standard Smith-Chart stuff.
Unfortunately, many ham SWR meters are not "good" and give misleading
results when presented with the above situation.
If the line is not lossless, then the SWR will decrease as you get farther
away from the load. This effect can normally be ignored for reasonable line
losses and line lengths.
References: Any ARRL Handbook or Antenna Book, Reflections by Maxwell, W6DU.
73,
Hank W6SX
w6sx@ptw.com
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