Characterization of the Vector Network Analyzer used as primary S-parameter standard

In recent years for the realization of the scattering parameters (S- parameter) primary standard INRIM adopted a software called VNA Tools II developed by the Federal Institute of Metrology METAS, the Swiss NMI. This software guides the user through all the measure- ment process providing, in the end, the measurement result and its uncertainty, in a way compliant with the Guide to the Expression of Uncertainty in Measurement - GUM. To evaluate the uncertainty of the S-parameter measurements, the software uses an internal database that contains all the uncertainty sources necessary for the computation. Those values can be either ex- tracted from the manufacturer specifications or they can be measured on the actual instrument used in the laboratory, strategy gives the most realistic and precise characterization of the set-up employed. This report describes the characterization procedure of the VNA used to realize the S-parameters primary standard to obtain the data necessary for the VNA Tools II database.