Synthesis of Large-Scale Concentric Ring Arrays for High Sparsity and Wide Scanning via Alternating Optimization

While phased arrays (PAs) offer flexible beam forming and wide-angle scanning capabilities, the high cost of transmit/ receive (T/R) modules significantly limits the development of large-scale arrays. This study addresses the optimization design problem of large-scale sparse concentric ring arrays (SCRAs) for wide-angle scanning with suppressed sidelobes under practical constraints. To address the challenge of co-optimizing array sparsity and beam scanning performance, this study first introduces the concept of the sparsity lower bound (SLB) to thoroughly account for the effect of neglecting higher-order harmonics on approximation calculations. Next, by decoupling the dual optimization variables (ring radius and weights) in the sidelobe minimization problem, an innovative array configuration design framework based on alternating iterative optimization is proposed. To increase algorithm robustness, a Gompertz curve model is introduced to establish an efficient initial solution selection mechanism. Multiple examples show that the array optimization achieved by the proposed method is highly competitive. The most notable achievement is the achievement of a wide-scan sparse CRA with 176,697 elements (35.08% of the fully populated array), an ultralow sidelobe level of -48.48 dB, and an optimization time of only 732 seconds.