A convex optimization based multistage wideband pattern accurate synthesis method for overlapping subarrays

Abstract

Due to frequency variation and overlapping architecture, some overlapping subarrays may exhibit significant grating lobe problems in their wideband patterns. Furthermore, accurate synthesis methods for wideband patterns with subarray architecture are lacking in traditional approaches, as they cannot control sidelobe level (SLL) accurately while maintaining a narrow half-power beam width (HPBW). To address these challenges, this paper proposes a multistage control approach for achieving precise wideband pattern synthesis of subarray structures. Firstly, we propose a subarray pattern synthesis method based on multi-frequency null control (MNC) to address the grating lobe issue under specific overlapping architectures. Secondly, building on the MNC method, we introduce an improved approach called single-frequency null control (SNC) to enhance the array degrees of freedom utilization. Thirdly, we propose an array factor synthesis method based on multi-frequency minimum mainlobe width (M3W) to accurately control SLL and minimize HPBW. This method leverages the subarray pattern synthesis outcome and enforces the multi-frequency SLL constraint to minimize the mainlobe width. Finally, we validate our proposed methods by comparing wideband array patterns, integration array patterns, and traditional methods. The simulation results demonstrate that our methods offer superior GLL suppression, accurate SLL control, and HPBW minimization. Furthermore, the proposed techniques can be applied to arbitrary overlapping subarray systems without being affected by grating lobes, thus overcoming a limitation of traditional methods.