Complete characterization of rectangular waveguide measurement standards for vector network analyzer in the range of millimeter and sub-millimeter wave frequencies

This paper describes a complete dimensional evaluation technique andelectrical characterization of waveguide shims as primary standards suitable for vector network analyzer (VNA) calibration at millimeter-wave and sub-millimeter wave frequencies. The NMIJ has established techniques for dimensional measurements of aperture size and for evaluating aperture corner radii and flange misalignment. Scattering parameters for the waveguide shim were calculated both from basic electromagnetic theory and by computer simulation. Surface roughness was also evaluated as it affects the transmission loss of a waveguide shim. In this paper we summarize the evaluation and calculation of waveguide shim standards, discuss the reproducibility in VNA measurements and consider extensions of the method to waveguide shims with smaller aperture sizes.