Modification of waveguide flange design for millimeter and submillimeter-wave measurements

Waveguide flange design makes major impact to measurement reproducibility in the range of millimeter and sub-millimeter-wave frequencies, e.g. above 110 GHz. Original concept of flange design, so-call “Oshima” flange, was established in the early 2000s. Its flange alignment is ensured using ring with tight tolerance, however, it is not compatible to MIL-DTL-3922/67C (UG-387) flange. This paper describes a modification of “Oshima” flange in order to establishing a compatibility with UG-387 flange design, and evaluation result of its capability of connection repeatability in the WR-3 (220 GHz-330 GHz) frequency band. Furthermore, the quarter wave length shim, as a TRL “through” line standard, is specially modified to fit with a new design of “Oshima” flange, then, its capability of connection repeatability is also measured and discussed.