Micromachined ridge gap waveguide for sub millimeter and millimeter wave applications

High-frequency waveguide technology has become a field of great interest lately. In this paper we present a ridge gap waveguide with two 90 degree bends and a ridge gap waveguide resonator, both fabricated with MEMS technology. It is the first time the ridge gap waveguides have been fabricated for millimeter waves. The ridge gap waveguides is realized of two conducting plates, one of them with a texture, and can provide low transmission losses without any requirements to alignment between the two plates, and with neither conductive joints nor sidewalls. The Ridge gap waveguide makes use of a ”bed of nails” structure which acts as a magnetic conductor and creates a cut-off for parallel plate modes between the two plates. Thereby, wave propagation is confined to the electric conducting ridge, without making use of electrically conducting sidewalls. MEMS technology can provide precision machining which makes it possible to go up in higher frequency bands than with conventional machining. The purpose of this paper is to describe the the fabrication process of the surface textured with pins and ridge.