Whatever, but what I'm trying to arrive at is a circuit simulation
which will enable the modulus and phase-angle components of reflected
waves to be displayed via Spice. If you or anyone else can come up
with an accurate way of doing so, then I'd be interested to hear about
it.
Easily done.
The biggest problem is the S Parameters vary with bias on the Transistor.
But you should get reasonable results at different bias points off a good
Spice Model.
I have an old 2 page App Note from Wes Hayard (W7ZOI) in DOC format that
describes a setup that will work in all the various Spices. If you provide
an address (suitably camouflaged) I'll send it.
But essentially you drive the device you want to measure the S Parameters
with a 2 volt AC source through a 50 ohm series resistor. The other end of
the source is tied to ground. That is, if the impedance of your system is 50
ohms.
In shunt with this connection to the device is one side of another 1V AC
source, set so it subtracts 1V of the applied 2V signal on the side not
connected to the device input.
That side of the 1V AC source is tied to ground through a high value (1Meg)
resistor.
Then the voltage at the top of that high value resistor will be S11.
If you tie the output connection of the device you're trying to measure the
S Parameters to 50 ohms to ground (use a coupling cap if necessary) then the
voltage at the top of that 50 ohm load to ground will be S21.
Turn this around to measure S22 and S12.
Robert