Research On Low Sidelobe Synthesis Method Of Non-uniform Array Antennas

Modern military,communication systems and other applications pursue better sta-bility and anti-interference ability,which puts forward higher demands on the sidelobe level of array antennas.Traditional uniform arrays are difficult to meet the desired perfor-mance requirements under the constraints of cost,weight,and complexity.Therefore,the research on the low sidelobe synthesis method of non-uniform array antennas has become a research hotspot in recent years.Sparse array and subarray partition,as two important methods,have been widely concerned by scholars.Sparse array can weaken the cou-pling of array elements,reduce the number of array elements greatly,and save the cost of array antenna surface by means of sparse array element number and random location arrangement.The subarray partition technology can reduce the design complexity of the feed network through the array processing method at the subarray level and thus save the cost of the feed network.The compromise between array performance and manufacturing cost can be achieved by sparseness and subarray partition,which has broad application scenarios and important research value.This thesis takes sparse array and subarray as the foothold,studies the low sidelobe synthesis method of non-uniform array antenna,uses the idea of hybrid solution to solve complex optimization problems,and completes the low sidelobe synthesis of the pattern through quantitative array elements.The main innovations are summarized as follows:1.A hybrid iterative Fourier and convex optimization(IFT-CVX)method is proposed to solve the problem of layout optimization and low sidelobe synthesis for any given sparse rate.The method uses iterative Fourier technology to obtain the initial thinned array that satisfies the preset thinned ratio.Lists the mathematical model of the optimization prob-lem,and realizes the transformation from the non-convex optimization problem to the convex optimization problem through the Taylor expansion of the element position vari-ables.The convex optimization algorithm is used to further optimize the element positions of the initial thinned array,and the sparse array with better sidelobe performance is finally obtained under the same thinned ratio.Compared with the existing sparse array synthesis method,the sidelobe level synthesized by the proposed method is reduced by 2.2?5.3 d B.Numerical simulation results show that the proposed method is effective in solving the low sidelobe synthesis problem of sparse arrays.2.An optimization method based on artificial bee colony,non-uniform Fourier tech-nique and fuzzy C-means clustering algorithm(ABC-NUff T-FCM)was proposed to solve the problem of subarray structure optimization,position optimization and low sidelobe synthesis of non-uniform array antenna based on subarray partition.Among them,the artificial bee colony algorithm is used to optimize the spacing of the array elements and generate a population with a non-uniform array layout.Under the feasible solution of any set of fixed positions,the subarray structure and excitation are optimized by combining non-uniform Fourier technique and fuzzy C-means clustering algorithm to achieve subar-ray partition at lower sidelobe level.Through such iterative process,the global optimal solution is finally obtained.Compared with the existing subarray partitioning method,the sidelobe level synthesized by the proposed method decreases by 0.92?7.9d B under the condition of saving the same feed points.Simulation results verify the effectiveness of the proposed method in solving the subarray partition low sidelobe synthesis problem.