Design considerations and technology assessment of phased-array antenna systems with RF MEMS for automotive radar applications

Planar array antennas are attractive for use in future automotive radar systems due to their flexibility in design and control of radar beams. The complexity and cost of a radar front-end phased array can be decreased by applying a beam-steering/switching concept, which reduces the number of parallel RF and baseband signal paths. RF-microelectromechanical systems (MEMS) subsystems are employed because of their excellent RF properties and potential low-cost manufacturability. We present design considerations for prototypical automotive applications of RF-MEMS-based automotive radar front-ends using phased-array antennas based on phase shifters or a Rotman lens. The single RF-MEMS switch is optimized with respect to its RF and thermomechanical behavior taking into account automotive requirements. The respective RF-MEMS subsystems, i.e., phase shifters and single-pole-multiple-throw switching networks are presented in conjunction with packaging and mounting approaches. We evaluate two different wafer-level packaging technologies using glass-frit sealing or polymer sealing. Finally, functional packaged devices are demonstrated: a glass-frit-sealed and flip-chip-mounted RF-MEMS switch and a benzocyclobutene-packaged single-pole-quadruple-throw switch network.