Residual error analysis of a calibrated vector network analyzer

With S-parameter measurement uncertainties reaching accuracy limits far beyond those previously achieved, uncertainty evaluation methods need to be advanced as well. A method based on Fourier analysis is presented for uncertainty analysis of one-port Vector Network Analyzer (VNA) measurements. The new uncertainty assessment method is validated using a system-level VNA model designed in Advanced Design System (ADS) software. The model replicates a one-port airline measurement system and allows for simulation of typical measurement scenarios including different residual error levels. The simulated airline measurement data is used to validate the proposed uncertainty assessment algorithm and to find the right gating window in the Fourier analysis. One of the main analysis results for 3.5 mm precision connectors is that airlines of 15-cm length should be used in uncertainty analysis of calibrated one-port VNAs using the Fourier analysis method. For short airlines the frequency dependence of the residual errors and airline termination lead to much higher estimated VNA uncertainties.