Dual-Circularly Polarized Reflectarray Based on Polarization Selectivity of Single-Fed CP Antenna Element

This communication presents a dual-circularly polarized (dual-CP) reflectarray (RA) based on a single-fed CP antenna element to achieve independent beam control. A novel methodology is proposed for designing the dual-CP RA, utilizing the technique of element rotation and true time delay. Contrary to traditional methods, it separates LHCP and RHCP waves into different channels and achieves independent manipulation simultaneously, based on the polarization selectivity of the CP antenna element. The proposed CP antenna element consists of a branch line coupler and a square patch. The received RHCP wave is adjusted by a phase delay line connected to its port, while the LHCP wave is controlled by element rotation. Finally, a continuous phase compensation strategy is employed, and an RA antenna with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.4\lambda \times 8.4\lambda $ </tex-math></inline-formula> and a focal length of 0.86 times diameter is carried out. The experiment results demonstrate the independent beams pointing at (0°, −25°) and (0°, 15°) for LHCP and RHCP waves, respectively. The realized gain of each beam peaked at 24.1 and 24.0 dBic. The bandwidth with simultaneous 2 dB gain variation and 3 dB axial ratio achieves 23.4% (23.7%) for the LHCP (RHCP) beam, with a profile of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.09\lambda $ </tex-math></inline-formula>. The aperture efficiency is 28.8%.