>
>Vic Rosenthal wrote:
>
>>Jon, if you were right, SWR meters would be useless, since readings would
>>change
>>as cable lengths changed! You may be misled by the fact that in practical
>>systems, common-mode ('antenna') currents on the outside of the coax often
>>disrupt SWR readings.
>>
>
>Obviously, Vic, you've missed the whole discussion I have participated
>in. If my transmission line impedance is the same as the impedance that
>I am operating in, then you move along a constant VSWR circle as you
>change the length of transmission line. Yes, the SWR remains constant.
>But in the case that Rich is using here, our transmission line impedance
>is 93 Ohms and is not the same as the impedance of our "system" which is
>50 Ohms. I define the system impedance to be 50 Ohms because our exciter
>and SWR meter are based on 50 Ohms. If we define 93 Ohms to be the
>center of our Smith Chart, there is a constant VSWR cicle. However if
>you define 50 Ohms to be the center of the Smith Chart, your rotation
>around the 93 Ohm point is no longer centered on 50 Ohms! So you cannot
>say that the VSWR is constant. You've changed transmission line
>impedances!
>
? Yea, verily. .
- Rich..., 805.386.3734, www.vcnet.com/measures.
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