Research On New Vector Beamforming Method For Conformal Antenna Array

Array antennas are more widely used in today's communication applications.For the different application requirements in real-world situations,we need to synthesize antenna radiation patterns that meet different radiation requirements.The common pattern requirements are specific shaped patterns,low sidelobe level,and specific polarization characteristic.In this paper,the semi-definite relaxation method is applied into the vector beamforming synthesis problem,and some non-convex constraints in the original problem are relaxed.Then,the original problem is approximately transformed into a convex optimization problem,which can be effectively solved.First of all,this paper introduces the basic knowledge of array antennas,the research on array synthesis in the array antennas field,the development of synthesis optimization methods,and the application of semi-definite relaxation methods in the array antenna synthesis field.At the same time,the radiation array pattern principle,the radiation pattern parameters and polarization characteristics are also introduced.Secondly,this paper introduces the concept of semi-definite relaxation method.According to the definitions of realizable co-polarization direction and cross-polarization direction,a synthesis method to generate the linearly polarized shaped power pattern with control on cross-polarization level and sidelobe level for an arbitrary array is presented.The definition of the dynamic range ratio of the excitation amplitude is also introduced here.In the procedure of power pattern synthesis,the control of dynamic range of the excitation amplitude is transformed into the suitable constraint form for the semi-definite relaxation method.Therefore,the semi-definite relaxation method is further extended to synthesize linearly polarized shaped patterns with accurate control of sidelobe level,cross-polarization level and dynamic range ratio of the excitation distribution.The proposed method can be applied to arbitrary antenna arrays,and can take into account the diversity of the element antenna pattern in the practical array.The mutual coupling effects between the array elements in the practical array environment and the platform effects are also included by using the concept of active element pattern.Finally,array element position error,excitation amplitude error and phase error in the implementation of array antenna are analyzed.On the assumption that each type of these random errors obeys the Gauss distribution,the expectation of the antenna array power pattern is analyzed,and the theoretical formula of variance is derived.In addition,theoretical upper and lower boundaries on which the power pattern falls on with a given probability is derived by using the Chebyshev's inequality.