Concentric Ring Array Synthesis for Low Side Lobes: An Overview and a Tool for Optimizing Ring Radii and Angle of Rotation

A comprehensive review on the approaches for synthesizing low side lobe concentric ring array (CRA) antennas is given. An Iterative Convex Optimization (ICO) based array layout synthesis technique is proposed for peak side-lobe level (PSLL) minimization over a given circular field-of-view in steerable uniform-amplitude concentric ring array (UA-CRA) antennas. For a given number of rings and number of uniformly-distributed elements in each ring, the ICO algorithm optimizes the ring radii and angle of rotation, with possible constraints on the minimum element separation and largest array size. As compared to the existing UA-CRA synthesis techniques, the proposed method presents unique features as it combines the capability of optimization of angle of rotation of the rings and PSLL minimization for multiple elevation scan angles in a computationally-efficient and easy-to-solve procedure. Through numerical design examples, it is demonstrated how the ICO technique can be effectively used (i) to synthesize sparse UA-CRA topologies generating low PSLL steerable beams, and (ii) to assess and improve the PSLL suppression performance of various known optimization algorithms. Based on the UA-CRA topologies synthesized via competitive methods in the recent literature, a new set of improved array topologies are presented.