Research On Beamforming Of Airborne Conformal Phased Array Of UAV

Conformal antenna array is named for its element arrangement which is similar to any curved surface.Compared with the traditional planar array,conformal array has the advantages of small installation space,large scanning range and large radiation aperture.If the conformal array is installed on the outer surface of UAV,the aerodynamic performance and electromagnetic stealth performance of UAV can be greatly improved.Under the background of strong electromagnetic countermeasure,in order to improve the anti-jamming ability of airborne conformal array,this paper puts forward the research direction of UAV airborne conformal array beamforming technology.It mainly includes conformal array modeling analysis,sidelobe level optimization and conformal array adaptive beamforming.The specific research contents are as follows1.The far-field formula of electric field and the theory of electric sweeping are given.Then the electric far-field formula of conformal array is given.The formula can be used to describe the electric far-field of conformal array composed of arbitrary elements and arranged along arbitrary curved surface.On this basis,for the convenience of research,the far field of electric field of conformal array composed of point sources along arbitrary curved surface is derived.By comparing conformal array with plane array,it is proved that plane array is a special case of conformal array.Then the far-field patterns of circular array and cylindrical array are given by simulation.According to the theory of electric scanning,the beam scanning simulation of circular array and cylindrical array is completed.2.The side lobe level optimization method of conformal array is studied.Firstly,the basic concept and basic process of genetic algorithm are introduced.Then it is applied to the optimization of sidelobe level,and the flow chart of using genetic algorithm to optimize sidelobe level is given.The side lobe level optimization results of circular array and cylindrical array are given by simulation.Aiming at the low iterative efficiency of genetic algorithm.The improved particle swarm optimization algorithm based on genetic algorithm(GA-PSO)is used to optimize the sidelobe level of conformal array.The proposed GA-PSO algorithm takes into account the iterative optimization speed of particle swarm optimization and the global optimization ability of genetic algorithm.The simulation results of side lobe level optimization for circular array and cylindrical array also support the above conclusion.3.The adaptive beamforming technology of conformal array with mutual coupling is studied.Firstly,the array element is designed,and parameter range of the selected model of the array element are determined according to the patch antenna theory.Then,the GA-PSO algorithm is applied to further optimize the array element to make it conform to the UAV navigation frequency and suitable for array formation.Then,two commonly used adaptive beamforming methods are given.The classical method is difficult to solve the array matrix in real array.The method of measuring array matrix is given to solve this situation.The array matrix obtained by this method contains mutual coupling information,so it can be applied to conformal array composed of actual array elements.The effectiveness of the above method is verified by the simulation of linear array and ring array in CST Microwave Studio.