Anyone who knows how a directional coupler works is rolling around on
the floor laughing at the suggestion of sorting "forward current" from
"reflected current".

And I'm one of them. I've never said there existed such a device,
just that if it did exist, it would solve the measurement problem.
As it is, we haven't solved the measurement problem.

I've solved the measurement problem. I measured current and voltage
levels and phase of each.

I've measured time delay of current appearing at the coil output
compared to input.

We have directional couplers installed at 'X' and 'Y' and
we can in theory look at the phases of the forward and
reflected currents on each side of the coil. Will the
forward and reflected currents through the coil show
a phase shift or not?

With all the respect I can muster, here we go again Cecil.

Current is current. Voltage is voltage.

A traditional directional coupler works by comparing voltage across the
line at any one point to current in the line at that same point. The
current sampling device is summed at the operating frequency with the
voltage sampling device, and the resulting voltage is measured. When
voltage and current are in phase, the detected voltage levels add. When
they are fully out of phase they subtract.

Now we could build a transmission line system of measuring SWR that
would work the very same way (normally done at VHF). Or we could build
a line section that allows us to slide a probe along it and measure
voltage or current nodes and finding maximum and minimum calculate SWR.

In every single device we would be able to build, we would never be
able to sort reflected current from forward because current is current.
There really isn't any such thing as current traveling two directions
at one past one point in a system.

You have taken this argument to an absolute dead end, because you
insist current can flow two directions at the same time at one single
point in a system.

You are demanding a measurement method that uses a device that cannot
be built to measure something that does not exist. That is either
humorous, sad, or frustrating. It sure isn't science.

73 Tom