Influence of Nonideal Calibration Items on S-Parameter Uncertainties Applying the SOLR Calibration Method

For the seven-term, short-open-load-reciprocal (SOLR) calibration method to calibrate a four-sampler vector network analyzer (VNA), the expressions for the deviations of the seven error terms and of the measured S-parameters of two-port test objects from their true values are presented; these deviations are caused by the deviations of the reflections of the calibration elements (shorts, opens, and loads) from their ideal values. For the SOLR calibration, a reciprocal unknown network is used instead of a known through. The influence of a slightly nonreciprocal network on both the error term and the S-parameter deviations is also considered. The obtained sensitivity coefficients are useful for establishing the type-B uncertainty budget for S-parameter measurements. Moreover, the results give valuable information for the design of the calibration elements.