Jeff wrote:

There will NOT be standing waves and there will not be a voltage
maximum and a voltage minimum unless there is a transmission line.

Are you saying that for a standing wave to qualify as a standing wave,
the transmission line needs to be long enough for there to be a voltage
maximum a voltage minimum?



No, I think the point is that VSWR is the wrong quantity to be using
under those circumstances. It is possible to calculate what the swr
*would have been* IF the line had been long enough to observe a max and
min, but by its very name it is clear that it is not possible to
measure it directly and see a ratio of the standing wave due to the
shortness of the line.

No, the point is that VSWR, according to the laws of physics, can be
shown to be a voltage ratio under the conditions where such voltages
exist, AND and impedance ratio that has no dependance on line length.

In those circumstances a better solution would be to use return loss,
reflection coefficient or S11 etc. The fact that lots of people use VSWR
as a measure of a mismatch does not make it correct when it is not
possible to measure the VSWR directly by observing the ratio of the
standing wave.

It can be shown by the laws of physics the return loss, reflection
coefficient, or S11 etc. can be converted to VSWR.

Which convention you use for the measurement is relevant only to what
equipment you have on hand to do the measurement.

If you tell the grocer you want a pound of banannas and he gives you
2.2 kilograms of banannas because his scale is calibrated in kilograms,
are you going to get into a ****ing contest with him?


A load in isolation without any transmission line connected cannot have
a standing wave, but it is still common to quote the mismatch as a VSWR
which is plain wrong, but still very common.

A load in isolation has no source and is thus irrelevant to anything
in this discussion.

--
Jim Pennino