A radiation pattern diversity reflector antenna is investigated. Novel switchable frequency selective reflectors are designed and developed to construct a square corner reflector antenna. By controlling a switching device on the frequency selective reflector, one can make it opaque or transparent to a vertically polarized incident wave. This antenna is fed by a monopole. By configuring the switch states of the frequency selective reflectors, various beam shapes can be formed and steered. Measured results of the antenna show good agreement with the calculated ones.