Bandwidth Enhancement of Sequential Rotation Arrays Based on Characteristic Mode-Inspired Dual-Resonant LP Element

This communication presents a compact, broadband dual-resonant linearly polarized (LP) element aiming at enhancing the bandwidth of sequential rotation arrays (SRAs). The proposed LP element consists of a center-fed split-ring resonator (SRR) microstrip patch and a C-shaped capacitive slot loading. Characteristic mode (CM) analysis shows that the proposed LP element can excite two TM20modes in the LP state, resulting in broadband radiation performance across the X-band. Furthermore, by applying different sequential rotations and excitation phases to the element, it maintains broadband radiation performance, making it an ideal building block for SRAs and thus enhancing the array’s operating bandwidth. To validate the proposed method, a 16 × 16 SRA prototype for dual-circularly-polarized radiation is designed and fabricated using the proposed LP element. Experimental results demonstrate that the prototype achieves a joint 3-dB gain and axial ratio bandwidth exceeding 46.85% for right-hand circularly polarized (RHCP) radiation and 51.1% for left-hand circularly polarized (LHCP) radiation.