Broadband metallized plastic waveguide antenna with robust isolation interface at 77 GHz

A two-piece metallized plastic multichannel waveguide antenna comprising a novel high-isolation interface for automotive radar at 76 GHz to 81 GHz band is presented. The antenna contains three transmitters and four receivers. Each comprises a directive eight-horn linear array. All individual antenna elements are connected to the printed circuit board (PCB) through an innovative compressed waveguide interface combining 2-D polarization diversity and pseudoperiodic structures. A final prototype is fabricated employing injection molding, metallization, and soldering processes. Excellent performance is achieved, with a total efficiency up to 94% for channels from 76 GHz to 81 GHz, and an impedance bandwidth of 20.1%. Furthermore, the interface offers minimal coupling degradation over the antenna to PCB assembly tolerances. The design and fabrication method are an attractive alternative to conventional substrate-based antennas.