Single-Layer Broadband Circularly Polarized Reflectarray with Subwavelength Double-Ring Elements

Abstract
A single-layer broadband circularly polarized reflectarray with subwavelength double-ring elements is presented in this article. Compared to conventional λ/2 elements, the subwavelength one can obtain a better circular polarization performance. Then, by using angular rotation technique, a reflectarray with this type of elements is designed and implemented. The fabricated reflectarray demonstrates excellent performance of 40% 3-dB axial ratio bandwidth and 19.1% 1-dB gain bandwidth, respectively. Moreover, the highest aperture efficiency can reach as large as 50%.