How do you calculate s-params of a ?μ-wave amp with a component added to the common?

I am trying to figure out how to calculate the s-parameters of a common source/emitter amplifier with a component added between the source/emitter and ground; how would you express this as a 2 port network in a T-matrix (ABCD matrix)? would you have to do look at the high frequency signal analysis and then calculate h-parameters (or z-parameters), then convert to s-parameters? btw I do not have ADS software (free trials expired) and I am designing an LNA using MATLAB RF toolbox instead.