Pattern Synthesis Technology Of Large Antenna Array Based On Subarray Partition

Pattern synthesis is an important branch of array antenna technology.For large scale array antennas,the subarray partition technology can balance the pattern performance and the cost of engineering implementation,so it has very important applications in many military equipment(such as Aegis,THAAD,GBR,etc.).Subarray partition is a NP(Nondeterministic Polynomial)-hard combinatorial optimization problem,and its design will directly affect the cost of engineering implementation and the performance of transmitting beam.How to achieve optimal subarray partition faces many challenges.Aiming at some problems of large scale array subarray partition at present,on the basis of previous research,this thesis carries out the research on subarraying algorithm and corresponding pattern synthesis technology.The contents are summarized as follows:(1)A simple and effective two-stage optimization algorithm is proposed for the subarray partition of non-uniformly spaced linear array.Specifically,first,a pattern matching problem is established with the optimization variables of subarray layout,element position,and excitation weights; Because subarray partition and position adjustment represent the loss and compensation of degrees of freedom,the algorithm for solving this problem can be divided into two stages.Firstly,fix the position of the array elements,then the pattern matching problem can be transformed into a clustering optimization problem,and the K-means clustering algorithm is used to obtain the excitation weights of the array elements and the layout of the subarrays; Then,based on the array layout and excitation obtained previously,combining with Taylor expansion,the non-convex array element position optimization problem can be transformed into a convex optimization problem and optimized using an iterative convex optimization algorithm.Simulation results indicate that the proposed algorithm can synthesize patterns with lower sidelobe levels and smaller pattern matching errors using fewer subarrays than state-of-art algorithms and uniformly spaced arrays.(2)Electrically controlled scanning array is an important branch of array antenna synthesis.Aiming at the subarray partition problem of phased array with rectangular aperture,two-sizes square subarray partition scheme and tiling algorithm is proposed for high gain beam scanning.The proposed scheme consists of two-sizes square tiles,and the main task is to optimize their layouts in the array aperture.Specifically,firstly,all the layout cases of the subarrays in the array aperture is represented by a sparse dictionary matrix,and then an integer(”0-1”)programming problem that maximizes the generalized directivity is established.According to the characteristics of the problem,the discrete cuckoo search algorithm is improved to obtain the subarray layout; Then,a convex optimization problem is constructed with the goal of maximizing the directivity and the CVX toolbox is used to get the solution.Simulation results show that the proposed subarray design scheme and algorithm can effectively suppress gate lobes while saving control points,and can synthesize higher gain patterns compared to the domino-tiled array.(3)For the precise coverage problem of polyminoes for the planar array,a new subarray tiling framework is proposed,meanwhile,a novel iterative optimization algorithm for tetrominoes is proposed.Specifically,according to the characteristics that the flat-top pattern can be decomposed into multiple scanning beams,the phased array subarray tiling problem is transformed into a tiling problem for flat top pattern.Then,based on the excitation matching principle,an iterative optimization algorithm is designed for accurate coverage of the tetrominoes to obtain the subarray layout.Subsequently,a convex optimization problem that maximize the directivity for the corresponding scanning angles is constructed and solved using convex optimization algorithm.Simulation results show that the proposed algorithm can obtain the array subarray layout faster than state-of-art algorithms,and the synthesized pattern has higher directivity in the scanning range.