Influence of non-ideal line-reflect-match calibration standards on vector network analyzer S-parameter measurements

In this paper, an improved two-step method is presented for the sensitivity analysis of vector network analyzer (VNA) S-parameter measurements due to the non-ideal line-reflect-match (LRM) calibration standards. This improved method is based on the indirect uncertainty propagation mechanism, which is especially suitable for the S-parameter measurements applying the self-calibration technique. To further simplify the formula derivation, the deviation matrices [δA] and [δB] are newly defined to represent the uncertainties of the T-matrices of error boxes. With this definition, formulas for the deviations of device under test (DUT) S-parameters can be concluded as functions of [δA] and [δB] in a concise form. Eventually, by solving only three linear combinations of the elements from [δA] and [δB], the sensitivity coefficients of DUT S-parameters due to non-ideal LRM can be conveniently deduced in an analytical form. Finally, experiments are performed to verify the proposed method.