Scanning Beam Synthesis of Uniform Amplitude Sparse Concentric Ring Arrays Based on Ring Attitude Correction

Concentric ring arrays (CRAs) are highly regarded for their ability to produce nearly invariant radiation patterns and constant beam widths in azimuth planes. However, the scanning beam synthesis of sparse CRAs presents higher computational demands than conventional broadside beam synthesis, leading to the failure of approximation methods and challenges in large-scale array design. To address this, we propose a layout optimization method for sparse CRAs is proposed to minimize sidelobe levels while meeting physical constraints. Initially, the ring configuration is refined through scaling and rotational adjustments to maximize the degrees of freedom in scanning beam synthesis. To achieve this, we develop a second-order cone programming model based on Taylor expansion by considering variables including the radii and the azimuthal rotation angles of rings. Additionally, an adaptive sampling strategy for radiation patterns is proposed to reduce optimization resources by focusing on at least three one-dimensional planes rather than the entire two-dimensional space. To overcome the lack of foresight in iterative optimization, we design the initial taper density solution using linear programming. Multiple numerical experiments validate the effectiveness of the proposed method, demonstrating successful array synthesis across various scales and limited scan angles.