Determination of the Uncertainties of Reflection Coefficient Measurements of a Microwave Network Analyzer

A method that calculates the residual uncertainties of a microwave network analyzer for the frequency range of 300 kHz to 50 GHz is described. The method utilizes measurements on NISTcertified standards (such as an airline or load) plus additional measurements to estimate the combined standard uncertainties for measurements using the network analyzer. The uncertainties of the standards are incorporated by means of a Monte Carlo technique. The uncertainties assigned to a network analyzer then provide the basis for estimating the uncertainties assigned to devices measured using a network analyzer. The results of this method for characterizing network analyzer uncertainties are presented for several connector types. L Introduction W W (IK, crl ra W 0 Pa Vector network analyzers (VNA) are widely used to measure the scattering parameters of a variety of microwave devices. The scattering parameters are related to reflection coefficients and transmission properties of the microwave devices. Typical devices that are measured include attenuators, terminations, mismatches, and directional couplers. Proper operation of the network analyzer requires a “calibration” or “accuracy enhancement” which is accomplished by measuring a set of known devices (typically, these devices are opens, shorts, and fixed and sliding loads contained in a calibration kit) and comparing the measurements to a model of the device in the instrument. Differences between the measurements and model result in a set of Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000. n 1998 NCSL Workshop & S ymposiurn