Analysis of Vector Network Analyzer (VNA) Uncertainty Framework and Noise Model for Interferometer

Abstract

Vector network analyzers (VNA) are used for the characterization of radio frequency (RF) and Microwave devices. One of the most challenging aspects of RF measurements is quantification of the different sources of uncertainties associated with VNA measurements and subsequently propagating those un-certainties to scattering parameters. This is especially true for interferometer based VNAs used for characterization of extreme impedance devices. In this thesis an analysis of uncertainty framework for VNA is presented along with a noise model for interferometer modules. It consists of measurement noise, nonlinearity and calibration reference standard uncertainties along with ca¬ble and connector effects. The interferometer noise model presented can be simplified and implemented on standard VNAs for both reflection coefficient and transmission coefficient noise measurement estimation. This is verified through comparison of measurement and model data for different values of reflection coefficient and transmission coefficient at multiple frequency points from 10 MHz to 50 GHz frequency range. The one port calibration uses short, open and load (SOL) calibration technique along with the ability to include correlations among the reference standards which is useful for finding a better estimate of uncertainties due to VNA error terms. The effect of cable flexure and connector repeatability is also included in the overall uncertainty analysis. Furthermore, analytical equations for two port calibration are provided for future extension.