Target Location Research Based On Distributed Phased Array Radar

The technique of the Liquid Crystal Optical Phased Array(LC-OPA) is a real-time programmable and electronically controlled beam scanning technology, which plays a crucial role on many areas, such as space laser communications, laser radar, laser weapons and adaptive optical detection etc. LC-OPA is a low voltage driven optoelectronic device, using the material of nematic liquid crystal as the working medium of phase modulation. It has some obvious advantages such as inertial less, high precision, agile scan and low SWaP(size weight and power assumption). In this paper, a beam controlled algorithm and beam controller hardware architecture is studied by using the liquid crystal optical phased array as the core device. The main contents are as follows:1)A far-field beam coherent of the liquid crystal optical phased array of theoretical model is built. It can realize a smaller beam scanning jerks, and beam controlled algorithms such as dual beam generation. A "sub-aperture coherent" beam controlled method is proposed: Firstly, the theory and algorithms of the sub-aperture coherent is studied. Then the effects of the sub-aperture coherent method on the far field is researched. When the value of stepping angle step?? is less than the width of the beam main??, it can realize ultra-high resolution laser beam deflection. When the stepping angle step?? is close to the width of the beam main??, the beam worming steering is realized. When the stepping angle step?? exceeds the width of the beam main??, the dual beam scanning is realized. Finally, the beam scanning jerks can be reduced to 6μrad according to theoretical simulation.2) A probability model of target acquisition based on the features of optical phased array agile scanning is established. Also a rapid target acquisition method based on agile scanning properties is proposed. The relationship between the acquisition time and the acquisition probability is studied through methods of the raster scanning, spiral raster composite scanning and the “Gaussian agile scanning”. In this paper, a new method of “Gaussian agile scanning” is proposed. We assume that the uncertainty region is ?30 ?X ?30, ?30 ?Y ?30. That is, the number of scanning points in the uncertainty area is 3721. Theoretical simulation indicates that, under the condition of the acquisition probability of 70%, our “Gaussian agile scanning” method competes a scanning points reduction of 1000 compared with the the raster scanning and spiral raster composite scanning methods. On the other side, the acquisition probability improved by 15% with 3721 scanning points.3)An experiment platform based on liquid crystal optical phased array is set up to verify the method of the beam-forming. What’s more, research and verifications are done to confirm the correctness of the sub-aperture coherent beam controlled methods. Numerical ultra-high resolution beam scanning experiments using centroid method shows that the beam scanning jerk is 6μrad, which agrees with simulation results very well. The beam worming steering and dual beam scanning experiments are accomplished by obtain the beam deflection position using a high-resolution CCD. These also show good agreements with theoretical simulation results. All the experiments of the ultra-high resolution laser beam deflection, beam worming steering and dual beam scanning confirm that the sub-aperture coherent beam controlled method is correct.