Cecil Moore wrote:
(snip)
You are in a room with a 50 ohm transmission line routed
through a hole in one side of the room, across the room,
and through a hole in the other side of the room. You don't
know which is the source end of the line. A directional
wattmeter reads 200 watts forward power and 200 watts
reflected power but you don't know which direction is
forward. Here's a diagram:

200W-- 2 amps--
hole-------------------50 ohm coax-------------------hole
--200W --2 amps

Which direction is the standing wave current flowing?

Lets also say that the wavelength of the waves passing through this
transmission line are as long as the room is wide (one wavelength fits
inside the room.

Then we can say that at any moment when the instantaneous magnitude of
he current is not at zero (and it will pass through zero all along the
line simultaneously, right?), the current will going in one direction
in half of that length *with varying magnitude) and the other way in
the other half (also with varying magnitude). I am not saying that
the direction reversal will necessarily be at the center, but that is
one possibility.

For example, if we took a snapshot of the current, all along the line
at the moment it peaked it might look like thislength of arrow
represents current magnitude, and head shows direction)(view in fixed
width font)

.....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole

This is a snapshot of the current all along the line at an instant.

A quarter cycle later, the current would be zero, everywhere.

A half cycle later (than the first snapshot) it would look like this:

.....--- --- -- - - -- --- --- -- - - --......
hole-------------------50 ohm coax-------------------hole

This is the pattern the standing wave function describes. The current
at every point has one of two phases, which are 180 degrees from each
other.

Is this how you see it?