Research On Array Pattern Synthesis Methods Based On Subarrays

Array antennas are widely used in radar and wireless communications due to their advantages of high gain and low sidelobes.With the in-depth research on large arrays,reducing the difficulty of array fabrication and enabling the array to achieve better performance have become the focus of scholars.Therefore,scholars have proposed an array antenna based on subarray division,which refers to dividing the array into subarrays,and generating the target pattern by feeding the subarrays,which can effectively reduce the number of active antenna elements,and reduce the complexity of the feeding network and the manufacturing cost of the array.This array antenna can optimize the excitation amplitude and phase of the subarray to produce a pattern with better performance.Based on subarray,two array synthesis methods are proposed in this paper,and the principles of these two methods are introduced in detail,and relevant experimental examples are given.The main research contents are as follows:1.Based on the K-means clustering method and the convex optimization algorithm,a new method which is combining the two methods is proposed,and the new method is used to synthesize the single-beam pattern and the multi-beam pattern of the array.In this method,the K-means method is first used to determine the subarray grouping structure,and then the relevant grouping results and the excitation of each subarray can be obtained.However,the subarray excitation obtained at this time is not the optimal solution,so after determining the subarray configuration,the convex optimization algorithm is further used to optimize the subarray excitations.Several experimental examples are presented to illustrate the effectiveness and applicability of the proposed method.These experimental results show that this method can effectively reduce the number of active elements and the complexity of the feed network.Also,the sidelobe level obtained by this method will be lower than when the K-means method is used alone.These experimental results also prove that the method is not only suitable for focused-beam pattern,but also for shapedbeam pattern.In addition,the method also has good performance results for real arrays and other numerically element-spaced arrays.2.Based on the convex optimization algorithm,a sequential convex optimization method is proposed and used in the shaped-beam pattern synthesis of the modular phased array.In this method,the domino-like subarray structures need to be determined first and the array is grouped with these structures,which can be solved by the convex optimization algorithm,then the relevant array grouping and subarray excitation can be obtained after the solution.Since the subarray excitation obtained by this method is not the optimal solution,further optimization of the subarray excitation by the convex optimization algorithm is also required.Several experimental examples are listed to illustrate the effectiveness,advantages and disadvantages of the proposed method.The experimental results show that this method can obtain better main lobe performance,but due to the reduction of freedom of the feed point,the optimized sidelobe level is higher than the side lobe level in the target pattern.Overall,the method can still produce good results in the synthesis of shaped-beam pattern.