W-Band RF-MEMS Subsystems for Smart Antennas in Automotive Radar Sensors

摘要

Future automotive radar systems can be realized using smart antennas, which offer a flexible design and control of radar beams. In addition, the complexity and cost of the automotive radar frontend can be reduced. RF-MEMS subsystems are employed for beamsteering in phased array systems due to their excellent RF properties and potential low-cost manufacturability. We present W-band RF-MEMS switches and RF-MEMS subsystems for beamsteering in phased array antennas based on phase shifters or a Rotman lens. The single RF-MEMS switch is optimized with respect to its RF and ther-momechanical behavior. Further, coplanar passive components, such as 90° bends and T-junctions are optimized separately. Using these switches and passive components, single-bit stub-loaded-line and switched-line phase shifters for 45° and, respectively, 90° or 180° phase shift are demonstrated with very good phase accuracy. For beam switching of a Rotman lens, we further present single-pole-multiple-throw RF-MEMS switching networks. In addition, a packaging approach based on glass-frit sealing with planar package feedthroughs and a flip-chip interconnect to microstrip lines on the RF circuit board are presented. We finally demonstrate a functional sealglass-packaged and flip-chip-mounted RF-MEMS switch.