Estimation of Complex and Linear Uncertainities in S-Parameter Measurements for Metrology Applications

The present paper aims to develop a uniform procedure of estimating uncertainty components in VNA measurements whether in complex or linear units. The individual response of each uncertainty components have been studied in the frequency range 1 to 18 GHz, which are applicable for one-port and two-port measurements. The Vector network analyser (VNA) measurements are performed to assign an overall uncertainty for the respective measuring parameter in terms of complex and linear units for coaxial step attenuator, fixed attenuator and mismatch. These measurements are then verified through the primary and transfer standards of the attenuation and impedance parameters and thus the traceability of the VNA measurements is established. Finally, the outcome of complete study has been presented as VNA measurements based new calibration and measurement capabilities (CMCs) for NPL, India. It has shown that the final combined uncertainty is found same or nearby by obtaining from uncertainty components either in complex or in linear units. Thus, this paper reports the estimation of VNA measurement uncertainties for various parameters as per the requirements of ISO/IEC 17025:2005 standard.