Measurement uncertainty in waveguide VNA calibrated by offset short calibration with oversized waveguide aperture at sub-millimeter wave frequency

This paper describes a new concept of calibration standards for waveguide Vector Network Analyzer (VNA) measurement in the millimeter and sub-millimeter wave frequency bands. High precision and traceable scattering parameter measurements have been established by using precision design of waveguide interface [1] and optimizing the measurement condition and setup of measurement system [2]. Even if using precision machining to make a precision waveguide, there is non-zero mechanical tolerance providing the degradation of connection repeatability. The National Metrology Institute of Japan (NMIJ) proposes to use the waveguide standard line with oversized aperture compared to aperture size of test-port waveguides. This new concept provides to improve the connection repeatability coming from misalignment. Results of the measurements and uncertainty estimation are described, and then, comparison results between conventional and new concepts are described for measurement uncertainty.