An improved estimation method of 4 port S-parameters with 2 port measurements

An estimation method for the S-parameters of 4-port connection circuit connecting a 2-port device to its one end is presented with a novel algorithm to improve the estimation accuracy. The 4-port S-parameters for the connection circuit are estimated using indirect measurements where several known loads are connected to the 2 ports at the far end of the connection circuit, where a 2-port device is to be connected, in turn and the reflection and transmission characteristics among the near end 2 ports of the connection circuit are measured. The estimation method is constructed in the framework of linear algebra that eliminates the needs to solve nonlinear equations numerically, which also enables application of theoretical analysis to this method. This method can be applied to obtain the S-parameters of the 2-port device connected at the far end of the connection circuit by de-embedding the estimated 4-port connection S-parameters.