A large steerable-beam antenna can be built by using a number of independent reflectors that redirect energy from a desired direction to a focus. An experimental program of measurement has determined the radiation pattern, the efficiency, and the relative change of gain and antenna temperature vs. beam angle of a test section of a multiplate antenna. The effect of the interstices in the reflecting surface produced grating lobes of approximately -20 dB and an additional temperature component that varied from 20°K-65°K depending on the beam angle.