An estimation method for the 3 port S-parameters with 1 port measurements

An estimation method of the three-port S-parameters for reciprocal circuits is presented. In this method, several known loads are connected to two of the ports and reflection characteristic of the remaining port is measured. Therefore, there is no need to connect network analyzer to the ports which are connected to the known loads. S-parameters are obtained by solving a linear system equations and quadratic equations only. In addition, a method for determining the port voltages from the estimated S parameters is also described, Then applying this method to estimate the S-parameters of an immunity test system, validness of this method has been confirmed. The proposed method will be applied when there is no common ground between each ports.