Synthesis of Wideband Rotationally Symmetric Sparse Circular Arrays With Multiple Constraints

Wideband rotationally symmetric sparse circular arrays (RSSCAs) with multiple constraints are synthesized in this letter. First, the circular aperture is partitioned into several rotationally symmetric sections, and each section consists of some annular sectors (ASs). The element positions and element numbers in these ASs are optimized. Taking the peak sidelobe level as the fitness function, and using the total number of array elements, the aperture size, and the minimum spacing between two adjacent elements to form multiple constraints, we formulate the synthesis problem as a constrained optimization problem. Then, the optimization technique is developed. By defining a projection process, the constrained optimization problem is transformed into a new constrained one with only box constraints, which is solved by the improved harmony search algorithm. During the optimization process, the infeasible solutions are avoided. As a result, the optimal element positions in the ASs are obtained. Finally, three synthesis examples are presented. Comparisons with some synthesis results in the literature indicate that our RSSCAs achieve relatively lower sidelobe levels over the wider bandwidths.