An introduction to the optical commutator

This paper describes a new device called an optical commutator. It is shown that this device can provide the time delays needed for true-time steering of an antenna array. The optical commutator consists of a rotatable folded lens comprising a set of fiber-optic coils arranged on a rotor and other fiber optics arranged on a stator. The beam steering is achieved by simply rotating the lens. The design theory of the commutator is described and equations are derived that allow the fiber-optic coil lengths of the windings to be determined for a given antenna performance specification. It is shown that the commutator can be designed to steer either flat, circular, or cylindrical arrays. The bandwidth of this concept is predicted to be significantly broader than any existing phased-array systems and that due to the simplicity of this system, considerable savings in both cost and weight should be possible when compared to present phased-array steering approaches. An optical commutator has been constructed to verify the design concept, and timing measurements have been made that validate the design.