Using simple calibration load models to improve accuracy of Vector Network Analyzer measurements

Abstract

A simple technique is presented that significantly improves the performance of some conventional. vector network analyzer (VNA) calibration routines. This, in turn, provides greater accuracy of measurement for the calibrated VNA. The technique relies on using `traceable¿ measurements at DC and high frequencies to characterize the VNA¿s load standard, used during calibration, in terms of polynomial fits to the measurement data. The method can be applied to calibration schemes that use a load (i.e. a `match¿) to provide an assumed known value of reflection during the calibration process (e.g. SOLT, TRM, LRM, etc). The method can be implemented in most types of commonly used transmission lines (e.g. coaxial line, co-planar waveguide, micro-strip, etc). The paper gives results illustrating the performance of the technique applied to a VNA operating to 3 GHz in coaxial line, calibrated using the SOLT technique.