<title>Acoustic-optic techniques for phased-array antenna processing</title>

Abstract

Abstract An acousto-optic phased array antenna beamformer with independent phase and carrier control capability is experi-mentally demonstrated using single-sideband signals driv-ing two acousto-optic devices. A dynamic range of 66.6 dB@+2 MHz and carrier-to-noise of 126.9 dBIHz @+2 MHz is measured. This beamformer has wide antenna tunable bandwidth and intrapulse beamforming capabilities. L Introduction Phase-based optical beamformers employ the phenomenonof controlled optical interference, with the particular inter-ferencelphase pattern oscillating in time at the desired radarmicrowave frequency [1,2]. By spatially sampling this in-terference pattern with a fiber/detector array, it is possibleto simultaneously generate all the correctly phased signalsfor pointing the array antenna beam in a desired direction. It is widely known that optical interferometers are highly sensitive to mechanical vibrations and other system insta-bilities, which in turn leads to phase instabilities in the out-put microwave signal.Recently, we proposed and experimentally demonstrated anovel in-line additive acousto-optic (AO) beamforming ar-chitecture that has excellent interferometric/phase stability[2-4]. One unique property of this AO beamformer that wasexperimentally demonstrated was the position coding of the