W-band RF-MEMS subsystems for smart antennas in automotive radar sensors

Future automotive radar systems can be realized using smart antennas, wbicb offer a flexible design and control of radar beams. In addition, the complexity and cost of the automotive radar frontend can be reduced. RFMEMS 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 sbifters or a Rotman lens. The single RFMEMS switch is optimized with respect to its RF and tbermomechanical 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 sbifters for 45" and, respectively, 90" or 180" phase shift are demonstrated witb very good phase accuracy. For beam switching of a Rotman lens, we further present single-pole-multipletbrnw RF-MEW switching networks. In addition, a packaging approach based on glass-frit sealing witb planar package feedthrougbs and a flip-chip interconnect to microstrip lines on the RF circuit board are presented. We fmlly demonstrate a functional sealglasspackaged and tlip-chip-mounted RF-MEMS switch.