Low-profile dual-CP antenna array using spiral sequential rotation technique for satellite communication

Abstract A low-profile dual-circularly polarized (CP) antenna array using spiral sequential rotation (SSR) technique is proposed. The array element consists of two stacked CP patches and a double-layer ceramic substrate with high dielectric constant. Dual CP radiations are accomplished by the slender rectangular structures on the radiators, which can excite two orthogonal characteristic modes. An extremely small size of 0.005λ 3 (λ is the wavelength in free space for the low bands) and a wide 3-dB axial ratio beamwidth (ARBW) of 206° are achieved. Furthermore, the SSR technique is employed to achieve low cross-polarization level (XPL) within a large scanning angle. Prototype of a 6 × 6 array was fabricated and measured. Experimental results demonstrate that a wide 3-dB AR scanning angle of ± 55° is realized for LHCP as well as RHCP radiation. Additionally, low XPL less than −18.1 dB with gain fluctuation less than 4 dB are achieved over −55° ∼ + 55°. Meanwhile, the array has successfully passed the mechanical test and the thermal vacuum test (−90° ∼ + 90°). All the merits of dual-CP radiation, extremely low profile of 0.06λ, wide 3-dB AR scanning capability, and low XPL make our proposed dual-CP SSR antenna array be attractive candidate for satellite applications.