This paper describes a silicon micromachined radar frontend. The designed frontend system includes active and passive elements within a single silicon chip due to the high integration capability of silicon micromachining techniques. The active part includes a switching circuit, and the passive part consists of a beam steering and beam shaping network and a 2×8 array antenna. The frontend has two WR-3.4 standard waveguide ports, and each port can create two frequency steerable radiation patterns controlled by the switching circuit. The return loss of both ports is better than 10 dB at 220-267 GHz for both beam shapes. The size of the whole system is 14.3×20×1.2 mm, and it can be used in imaging, tracking, and surveillance applications.