Numerical method for obtaining the scattering matrix of a microwave two-port from standing wave measurements

A numerical procedure is presented for obtaining the scattering matrix of a passive reciprocal two-port from eight standing wave measurements with the aid of an image circle in the Smith chart. The optimum circle through more than three points is defined. Furthermore, an averaging method is applied using the fact that theoretically after a certain transformation the experimental points should be distributed regularly on the circle. The procedure is programmed for a computer.