Calibration of test fixtures using at least two standards [microwave circuits]

The determination of the error networks in measurements of microwave circuits with arbitrary test fixtures is studied. A general-purpose deembedding method for known standards is shown. Also, a method for symmetrical test fixtures is described. The method uses only two fixture standards, of which one must be a two-port standard with a transmission not equal to zero. A computer simulation is used to compare the error sensitivities of the different calibration algorithms. The main advantage of the methods described is that the standards can be modeled freely and any idealization or restriction to certain special standards is not necessary. Any kind of standard can be used if the S-parameters are known or if a circuit model for the standard can be determined. Also, the dispersion of the microstrip line standards can easily be taken into account