Fabrication of calibration standards for the millimeter- and sub-millimeter wavelength ring-centered waveguide flange

This paper introduces a new fabrication approach for calibration shims with ring-centered waveguide flanges using KMPR based microfabrication. The high precision of the ring-centered flange imposes more strict restrictions on the dimensions of corresponding waveguide shims, making conventional machining techniques less competitive. Taking advantage of the KMPR microfabrication process, a set of accurate calibration standards (λ/4, 5λ/8 and 7λ/8) for the WR-2.2 band (330 GHz–500 GHz) ring-centered waveguide flange are fabricated and characterized. As a reference, a set of calibration standards for regular UG-387 flanges is prepared using the same approach. Measurement results and the comparison between the two sets of λ/4 waveguides are presented in the paper.