The location of certain types of communication and radar RF emitters is a critical concern for a variety of purposes relating to the national defense, particularly for tactical communications and the detection and avoidance of threat radars. Determination of the angel of arrival of an RF signal is currently accomplished by processing the signals from a 2D array of sensor elements. The signals are typically processed with the use of an RF combination network and the performance is severely limited by interference and multiple signals of interest. This paper describes an acousto-optic signal processing architecture that provides the angle of arrival unambiguously over 360 degrees. The system architecture is based on a circularly disposed antenna array. The optical system that processes the antenna element outputs is based on a new A-O device design concept presented in this report. The operational properties of the new Bragg cell concept are illustrated.
Todd R. Bader, Todd R. Bader,
"Acousto-optic direction-finding processor for circular array antenna", Proc. SPIE 3388, Advances in Optical Information Processing VIII, (25 August 1998); doi: 10.1117/12.319410; https://doi.org/10.1117/12.319410