A Programmable Lens-Array Antenna With Monolithically Integrated MEMS Switches

This paper describes a reconfigurable millimeterwave lens-array antenna based on monolithically integrated microelectromechanical systems (MEMS) switches. This device is constructed as a planar array of 2-bit programmable MEMS antenna-filter-antenna (AFA) unit cells that are used to provide a 1-D programmable "aperture transfer function" between the input and output wavefronts. The fully integrated device consists of 484 (22 x 22) AFA elements and 2420 switches. Switches, bias lines, antennas, and the rest of the RF structure are fabricated on two quartz wafers (epsilon(r) = 3.8, tan delta = 0.002) that are subsequently stacked using adhesive bonding to form the tri-layer metal structure of the AFA array. The bonded structure also forms a package for the MEMS switches. This paper investigates the design and fabrication issues and presents the measured data related to yield and frequency response of this lens-array. It also characterizes the performance of this device as a steerable antenna. Measured results show that this lens-array can be used to steer the beam of a low gain horn antenna to +/- 40 degrees in either the E- or the H- plane. For the fabricated prototype, the yield is estimated to be 50% for the best region of the array, resulting in a relatively high insertion loss and sidelobe level.