Coplanar 122-GHz Antenna Array With Air Cavity Reflector for Integration in Plastic Packages

This letter introduces the concept of a surface-mountable millimeter-wave radar sensor, which becomes possible by integrating the complete radar front end including the antennas into a single plastic package. The packaging concept is based on a matched coplanar wire-bond interconnect between the semiconductor die and the off-chip antenna. A 122-GHz antenna design is presented that uses an air cavity within the center die pad to improve the bandwidth-efficiency product. The antenna is designed in an array configuration to reduce the effect of surface waves. Measurements of the antenna prototype in the package, as well as a study on the influence of the package lid on the antenna performance, are given.