Integration of microwave MEMS reconfigurable reflective surfaces in rectangular waveguide stubs

This paper presents a novel method of integrating MEMS chips into rectangular waveguides, demonstrated for MEMS reconfigurable reflective surfaces mounted perpendicularly into waveguide stubs for creating W-band phase-shifters. A patterned double-side adhesive conductive polymer sheet acting as compliant interposer electrically connects and mechanically fixates the waveguide frame to the MEMS chip. Furthermore, DC biasing lines for reconfiguring the MEMS chip are embedded in the polymer frame, acting as waveguide feedthrough lines. MEMS tuneable reflective surfaces have been fabricated using this novel mounting method. Microwave measurements show that the novel conductive polymer interface has less than 0:4 dB loss as compared to a standard short. Conventional mounting methods for in-plane biasing lines, requiring an air-gap interface and thus not allowing for electrical contact between the chip and the waveguide, are shown to result in typically 2:5 dB losses for an air gap equivalent in size to the polymer frame. The measurement results are in accordance with FEM simulations carried out for different interface parameter variations.