Second-order error correction of a calibrated two-port vector network analyzer

A technique for second-order correction of the system error parameters of a calibrated two-port vector network analyzer (VNA) is described. The method is based on the determination of the complex-valued residual directivity, source match, and reflection tracking by one single reflection measurement at both ports employing a high precision airline terminated by a short. From one additional measurement of the through connection applying partly corrected system error parameters, the second-order corrected transmission tracking and the load match in both directions are calculated. Thus, a complete set of second-order corrected error model parameters is determined resulting in an accuracy enhancement. Furthermore, the differences between first- and second-order error parameters give a measure for the quality of the VNA calibration performed beforehand. Measurement results for a 10-dB attenuator are given and compared with data resulting from reference attenuation measurements.