Richard Harrison wrote:
. . .
Standing-wave ratio=S=Emax/Emin

This definition of standing-wave ratio is sometimes called voltage
standing-wave ratio (VSWR) to distinguish it from the standing-wave
ratio expressed as a power ratio, which is (Emax/Emin)squared."

Now, that's an interesting concept.

The VSWR is the ratio of the maximum voltage anywhere along the line to
the minimum voltage anywhere along the line (presuming the line is
sufficiently long for a full maximum and minimum to occur). We can use a
voltage probe to actually measure this voltage in a slotted line.

If the voltage is sinusoidal, so is the power, just at twice the
frequency. (I'm sure you can find that in Terman somewhere, but it's
simple to derive with a little trigonometry.) Since you say that power
superposes, we should expect power waves to add and cancel just like
voltage waves. And this should result in dips and peaks in the power as
we move along the line, just like voltage, right? I'd expect the dips
and peaks to be twice as closely spaced, however, because the wavelength
of the power waves would be half the wavelength of the voltage waves.

So is the ratio of the maximum to minimum power along the line due to
this superposition of power waves equal to the PSWR?

Roy Lewallen, W7EL