| The benefits of conformal arrays include reduction of aerodynamic drag, wide angle coverage, reduction of Radar Cross-Section (RCS) and elimination of radome-induced bore-sight error, etc. So conformal arrays will find their potential and promising applications in a variety of fields, ranging from space-borne, airborne, ship-borne, and missile-borne radar, space vehicles and wireless communications to sonar, etc. The antenna conforming to the shape of Millimeter Wave radar seeker surface can substitute the precise universal servo tracking system, have ability of more space and load to install new types of equipment, and then improves the system performance. Conformal arrays in millimeter wave radar seeker with optic/electric compound guidance system is of an innovative concept. This dissertation mainly study the technology about digital beam-forming methods for millimeter wave conformal array, and provide theory and technoligical support for the application of conformal array in millimeter wave compound guidence system.The research development of optimal beam-forming for conformal arrays at home and abroad is analyzed in detail. Then, around research tasks of Advanced Defense Research Programs of China and National Science Foundation of China, the principal study content about digital beamforming methods for millimeter wave radar seeker conformal array of this dissertation is:(1) aperture compound and parameter design in compound guided system, performance analysis and comparison of conformal array and planar array, performance analysis of conformal array seekers with different aerodynamic shape (geometry) and array configuration, optimal array configure method of conformal array, and low sidelobe beam-forming method for conformal arrays; (2) mono-pulse sum/difference beam synthesis method of millimeter wave radar seeker conformal arrays.The main content of this dissertation is summarized as the following chapters:Chapter 2 analyzes some performances of conformal arrays in millimeter wave optic/electric compound guidance system. Firstly, multi-mode seeker compound mode is discussed; secondly, in high speed applications parameter design of millimeter wave conical array is studied; thirdly, conformal array and planar array antenna models are established, and characteristics of scan beam are analyzed and compared; Finally, the quantitative analysis of beam scan region in millimeter wave conical array in compound guided system is studied. For the aperture compound problem of millimeter wave conformal array, based on the dichotomy of linear optimization, the conical array aperture programming method is proposed. Simulation results show that antenna patterns meet the requirements, and the advantages of multi-mode seeker are fully played with the given configuration parameters in high speed applications.In Chapter 3, the beam scanning characteristics of different aerodynamic shape conformal arrays in millimeter wave optic/electric compound guidance system, and array pattern performance of different conformal array configuration are studied. After analyzing the world's tactical missile in service, several typical aerodynamic seeker conformal array models are constructed, and the conformal array pattern synthesis models of arbitrary shape are established. With regular array configuration beam performance of different aerodynamic shapes is compared. Then the aerodynamic shape of the best performance is selected to analysis the beam performance of different array configuration. Simulation and experimental results show that, with rectangular grid array configuration, the scanning beam performance of conical array is optimal; and the rectangular grid array configuration is optimal in the optimal aerodynamic shape.Chapter 4 developes two optimization methods for array configuration of conformal arrays in millimeter wave optic/electric compound guidence system:(1) With triangular grid array configuration, a new subarray partition method is proposed, and based on subarray adaptive processing considering the polarization, the subarray configuration method is proposed. Simulation results show that the proposed method can effectively suppress the gatelobe caused by the subarray division and sparse array configuration, enhance adaptive subarray processing performance, and greatly reduce the computational burden. (2) Based on the optimal polarization mode, sparse array configuration method of conformal arrays is proposed. Simulation results show that the proposed method can greatly reduce the element density, and effectively suppress the gatelobe caused by the sparse array configuration.Chapter 5 mainly studies low sidelobe beamforming method of conical arrays in millimeter wave optic/electric compound guidence system. Firstly, the traditional plane arrays optimization algorithm based on adaptive array theory is given. Secondly, the alternating projection optimization method considering polarization mode is summarized. Thirdly, after the element polarization of conformal array is adjusted to be consistent, a multi-objective genetic algorithm, considering the sidelobe level, the array gain and the main beam width, is proposed. Lastly, the three optimization methods are used to synthesis low sidelobe pattern of millimeter wave conical array. Simulation results show that after polarization direction of all elements in millimeter wave conformal array achieve consistency, the method based on multi-objective genetic algorithm is have advantages in the cross polarization level, beam width and the array gain.When pointing direction offset the visual axial, conical array is unsymmetrical. In Chapter 6, to synthesize mono-pulse sum and difference beams for Millimeter Wave conical arrays, which the traditional divided method cannot afford, a novel approach based on the equivalence principle is proposed. Firstly, structure characteristics of conformal array are analyzed. Secondly, array element distribution is analyzed, when the beam direction is offset the visual axial. Thirdly, the incident coordinate system and the incident reference plane are constructed respectively. Lastly, the method based on plane projection and the method based on the equivalent principle are proposed to form the mono-pulse sum/difference beam of conformal arrays. Simulation results show that both methods can effectively form the sum/difference beam with the beam direction offset the visual axial, the method based on the equivalent principle can achieve better beam performance, but the method based on the plane projection is more flexible and rapid.Chapter 7 concludes this dissertation and some proposals for future work are also presented.
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