Research On Fast Synthesis Of Ultra-wideband Sparse Array

With the increasing application of ultra-wideband(UWB)array antennas in daily life,many researchers have gradually paid attention to innovations related to this kind of array.In particularly,how to synthesize the antenna parameters that can conform to the expected radiation performance under the premise of high computational efficiency has become a research hotspot.Combining sparse array’s superiority of making hardware system lightweight and decreasing development cost,the main research content of this paper is the rapid synthesis of UWB sparse array,which can be summarized into two parts:one is the rapid synthesis of UWB sparse array based on the improved iterative convex optimization(ICO)algorithm,and the other is the rapid synthesis of UWB sparse array based on the alternating projection(AP)algorithm.In the part of rapid synthesis of UWB sparse array based on ICO algorithm,the principle of classical ICO algorithm used for array elements perturbation to suppress the grating-lobes or sidelobes is first introduced,but this method has some shortcomings:1)The increase of linear array size will lead to the increase of the constraint dimension of the angle and the decrease of the computational efficiency;2)It can only be applied to the sparse synthesis of small-scale UWB planar arrays,which is not conducive to largescale array applications in real life.Based on these,this paper proposes two methods for de-redundancy of the sidelobe constraint region in the iterative convex optimization array synthesis:The first is to sort the lobes in the sidelobe area in descending order according to their peak level during each iteration.The first iteration only constrains the lobe where the maximum sidelobe level is located,and then adaptively increases the number of lobes in the sidelobe constraint region according to the sorting with the aim of steadily reducing the maximum sidelobe level output in each iteration;the second is to set a certain sidelobe region from the maximum sidelobe level in the array factor pattern vertically down as the optimized sidelobe constraint region.The constraint region is updated with the maximum sidelobe level in each iteration until the maximum sidelobe level converges.Through statistical learning of constraint parameters for different array sizes and verification of two specific arrays of arrays,the results show that both of these two methods can ensure the suppression of grating-lobes or sidelobes and greatly improve the optimization efficiency of the algorithm.Finally,the second sidelobe de-redundancy method is applied to the synthesis of ultra-wideband sparse pseudo-rectangular arrays.The experimental results show that this method greatly saves the time cost of pseudo-rectangular array synthesis and optimization.In the part of rapid synthesis of UWB sparse array based on AP algorithm,by improving the optimization model in the back-projection step,using the least squares model with constraints to simultaneously consider the constraints when solving the perturbation,instead of solving the perturbation first and then constraining,the problem of unstable sidelobe level convergence curve and oscillation is successfully solved.The grating-lobes or sidelobes of UWB array are robustly suppressed to a certain extent,and the time cost is not very high.