Research On Low Sidelobe Optimization Algorithm For Constant Amplitude Excitation Of Sparse Array

Sparse synthesis of array antenna is an important research content of array synthesis.With the reduction of the hardware complexity and cost of the whole system,it has been widely used in radar,satellite communication system and radio astronomy.The sparse array can be divided into two types: non-uniformly amplitude and uniformly amplitude.The uniform amplitude sparse array can greatly simplify the feeding network,which contributes to advantages in manufacture and maintenance.However,different element positions will cause great changes of sparse array pattern with equal amplitude excitation,and the sidelobe level of the pattern is usually high,especially when the scanning angle is large.Therefore,the position of array elements must be optimized to reduce the sidelobe level.The main research results of this paper can be summarized as follows:In the second chapter,the basic theory of antenna array is introduced,including the pattern multiplication principle and the electrical parameters of antenna array.Next,the sparse optimization method for mathematical models of linear array,planar array and concentric circular array are presented.In the third chapter,the deterministic sparse technique of weighted density method is applied to optimize different kinds of antenna arrays.To overcome the limits of the minimum element distance and sidelobe level in larger scanning angle,a differential evolution algorithm based on the random fluctuation model of Levy flight is proposed to optimize the position of the array element obtained by weighted density method.Moreover,we conclude that the bandwidth applicability of this method is narrow when analyzing the bandwidth applicability of three different planar sparse arrays.In the fourth chapter,a synthesis method of wideband sparse array based on covariance matrix adaptive evolution strategy(CMA-ES)is presented.The basic principle of the algorithm is introduced,and the performance of the algorithm is tested.This algorithm is used to accomplish the uniform-amplitude sparseness of small and medium-sized wideband linear arrays.By virtue of combining with rotational symmetry,the zoning optimization of broadband planar array is carried out.The uniform and non-uniform distributions in each region are discussed,and the effects of the number of regions and elements on the performance of the array are analyzed and discussed.