An Irregular Optimizing Design of Connected Vivaldi Array for Wideband and Wide-Angle Scanning

In this article, an irregular optimizing design method of wideband and wide-angle scanning array is proposed. The sparsity technology was first extended into the optimization of the arrangement of wideband-connected array components. By virtue of adjusting the width of the edge radiation wall, an optimal radiation distribution of a wideband array can be implemented, which also exploits more freedom of element distribution and characteristic design. Moreover, the advantage is that the connectivity between wideband antenna units and the continuity among array current distribution can be ensured. Though the optimized array layout can accomplish lower sidelobe level (SLL) with equal-amplitude excitation feed, it may also exacerbate the complexity of the mutual coupling (MC), which further affects the radiation characteristics such as bandwidth, voltage standing wave ratio (VSWR), and wide-angle scanning. Hence, the space mapping (SM) technique was introduced to accomplish the wideband irregular optimal design involving the MC effects for higher optimizing efficiency and accuracy. The genetic algorithm (GA) was incorporated with active element pattern (AEP) to further optimize the irregular array distribution for the coarse model of the SM design procedure, which involves the actual array element rather than the only array factor synthesis. A prototype array was made and measured, and the experimental results showed that the design results were in good agreement with the measurement results. Verified the efficiency of synthesizing array patterns with lower SLL and fewer Vivaldi elements in broadband and wide-angle scanning.