A tray based Rotman lens array with beamforming in two dimensions for millimeter-wave radar

A tray based Rotman lens array is presented, which consists of several low-profile Rotman lenses with beam control circuitry, miniature dual-polarized horn antenna arrays, and tray selection circuitry for elevation beamforming. The array achieves broad bandwidth from 34 to 40 GHz, and beamforming in two dimensions is realized. In azimuth, switched beamforming is implemented with the Rotman lens beam control circuitry. In elevation, adaptive beamforming using MUSIC (multiple signal classification) is implemented with the individual Rotman lens trays. A proof of concept beamforming experiment was conducted, where the locations of targets within a three dimensional space were detected with 2.5 cm range resolution.