Where do the coax, microstrip, stripline, and waveguide models come from?
The models are parametric-based and were developed using information found in the general literature. The approach to creating a model is to obtain the R, L_external, L_internal, G, and C from the formulas and than calculate the S-parameters for that transmission line segment. For coax and waveguide, it is pretty straight forward, but for microstrip and stripline, it is more difficult. I have put together a document that describes the formulas used to generate the models and where they came from.
