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

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

Schöbel, Jörg / Buck, Thomas / Reimann, Mathias / Ulm, Markus / Schneider, Martin

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 front end 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. W-band RF-MEMS switches and RF-MEMS subsystems are presented 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 thermomechanical 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, further single-pole-multiplethrow RF-MEMS switching networks are presented. 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. Finally it is demonstrated a functional sealglass-packaged and flip-chip-mounted RF-MEMS switch.