Acousto-optically controlled beamsteering techniques for MMIC-based phased array antennas

Future phased array antenna systems for radar and communications will utilize MMIC phase shifters and optical distribution techniques within a subarrayed antenna architecture. While significant progress has been made in the areas of photonic signal distribution in the last decade, relatively little effort has been directed towards compatibility with MMIC technology. This thesis presents both a theoretical and experimental investigation of two acousto-optically controlled array beamsteering techniques which are compatible with MMIC technology and subarrayed antenna architectures. The first technique explores the application of parallel optical signal processing within an acousto-optic cell to generate and distribute MMIC phase shifter control commands for array beamsteering control. This technique is analyzed from both a subsystem and system point of view and theory is developed which quantifies beamsteering performance with respect to noise, dynamic range requirements in both the microwave and optical domains, channel capacity, and the non-linearity of the acousto-optic cell driver. An experimental demonstration of the beamsteering control system was performed to validate the theory. The experiment was performed at L-band using a three bit MMIC phase shifter operating at 1300 MHz. Radiation patterns computed from experimental data show the correct steered responses. The second techniques explores the application of acousto-optic deflection in conjunction with high speed intensity modulation to generate programmable microwave time delays for true time delay beamsteering. Theory is developed which shows that there is no interaction between the optical sidebands generated in the intensity modulation process and the Doppler shift generated in the acousto-optic cell. The number of achievable delays as a function the acousto-optic cell parameters and the desired isolation between delays is also quantified. Experimental results are presented which validate the theory, showing 10 and 20 ns delays using external intensity modulation of a 1310 nm diode pumped solid state laser at 650 MHz.