Beamforming system based on paralleled variable chirped microwave signal generators

Optically controlled beamforming technology has attracted a lot of research interest for its unique advantages and application in phased array antennas (PAAs). In this paper, a novel scheme of an optically controlled beamforming system based on an array of chirped microwave signal generators is proposed. In the proposed system, an array of photonic microwave delay line filters (PMDLFs) with quadratic phase response is configured, and chirped microwave signals, which are then applied to the antennas, are generated by processing a chirped-free Gaussian pulse by those filters, and the relative delay among those chirped microwave signals can be controlled by tuning the optical carriers' wavelength in each path. Therefore, the system can realize optically controlled beamforming by successfully combining photonic generation of a chirped microwave signal with optical true time delay (OTTD). As the PMDLFs' frequency response can be flexibly varied, the generated microwave signal waveforms can be adjustable to suit the needs of different applications. A theoretical analysis of the proposed beamforming system is carried out and its feasibility is verified by numerical simulations. (C) 2017 Optical Society of America