rf toolbox "circuit" w/touchstones?

I am curious about analysis with s-parameters using the 'circuit' function from the rf tool box.

Is it possible to place rlc loads and other topologies on the pins of an arbitrary size touchstone file?

[MathWorks RF & Mixed-Signal Products Team]

Yes! It is indeed possible and quite simple. For an example, see at this MATLAB code:

%%Import the Touchstone file
sobj = sparameters('default.s16p');

%%Create a new circuit object
ckt = circuit('network');

%%Add the S-parameters to the circuit
add(ckt,[1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16], sobj);

%%Terminate ports 3 to 16 on 50 Ohm
% Could be any other lumped elements
for i = 3:16
    add(ckt, [i 0], resistor(50));
end

%%Compute S-parameters of ports 1-2
f = 1e9:50e6:5e9;
setports(ckt,[1 0], [2 0]);
S21 = sparameters(ckt,f, 50);

%%Plot results
Smag = 20*log10(abs(S21.Parameters(2,1,:)));
plot(f, squeeze(Smag),'bx');
hold on;
plot(sobj.Frequencies, 20*log10(abs(squeeze(sobj.Parameters(2,1,:)))));

I hope that this helps!