With 2-port S-parameters, you can build up a circuit by chaining them together using ABCD or T-parameters, simply multiply the matrices:

ABCD and T parameters

We have measured a complex single port S-parameter of an antenna. I would like to chain 2-port S-parameter impedance match matrices (from .s2p's) in front of the 1-port antenna measurement (.s1p) such that the result is a single port matrix of the entire system. Thus, the result is composed of several 2-port matrices (chained) and terminated by the 1-port antenna S-parameters, producing a 1-port matrix. This would allow us to estimate impedance match behavior for the antenna with the match.

Of course there are software packages out there that do this, but I am writing my own RF library in Perl and would like to add 1-port chaining as a feature.


First we have to transform the 1-port S-parameter matrix to "ABCD compatible" parameters so that they can be multiplied to the 2-port matrices. What is the math for that transform?

Is the resulting single port matrix simply multiplied against the 2-port ABCD- or T-parameter matrix, or does 2-to-1-port composition differ somehow?


1 Answer 1


From Wikipedia (or pretty well any rf/microwave text covering S-parameters):


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