Repeatability and Mismatch of Waveguide Flanges in the 500–750 GHz Band

This paper presents a study characterizing the connection repeatability and reflection coefficient of submillimeter waveguide flanges in the 500-750 GHz band (WR-1.5 or WM-380). The connection repeatability of four types of flange was measured using one-port measurements and a “load-reference” technique with a vertically mounted system to mitigate gravitational bias. To measure the error-corrected complex reflection coefficients of pairs of waveguide flanges, a calibration procedure insensitive to flange misalignment was used. This SDD(RO) calibration method employs four standards: a flush short, two delay shorts with different but unspecified offsets, and a radiating open-ended waveguide. The uncertainty associated with this calibration method is investigated and it is used to estimate the reflection coefficient resulting from flange misalignment.