Automatic Model Extraction of the Match Standard in Symmetric–Reciprocal–Match Calibration

This paper addresses the modeling of parasitics of the match standard in the symmetric-reciprocal-match (SRM) calibration method of vector network analyzers (VNAs). In the original SRM procedure, the match standard is assumed to be defined. Here, we demonstrate that the match can be modeled with an arbitrary frequency-dependent model using a non-linear global optimization procedure. To highlight the validity of the suggested approach, numerical tests were conducted, demonstrating the ability to recover the match standard parasitic model down to software numerical precision. Additionally, we performed microstrip line measurements on PCB to compare the SRM calibration using the proposed automatic model extraction against an SRM calibration where the match standard is explicitly defined via multiline thru-reflect-line (TRL) data. The results show that the automatic model extraction can achieve accuracy comparable to that of a data-based match definition, validating the approach as an effective substitute when explicit characterization of the match standard is unavailable.