An estimation method for 2-port S-parameters using 4-port connection circuit with leakage couplings

An estimation method for S-parameters of 2-port circuit by using connection circuits with leakage couplings is presented. In our method, two ports of 4- port connection circuit are terminated with unknown 2- port circuit or known loads. And the S-parameters between remaining two ports are measured. Advantages of our method is that the S-parameters of 2-port circuit are to be estimated only by solving the linear least squares problem. Our method can be applied to determine the S-parameters of the circuit with a difficult port to connect the probe of the instrument as the IC package and to determine the S-parameters of the circuit ground is not common.