Anisotropic Impedance Surface-Enabled Low-Profile Broadband Dual- Circularly Polarized Multibeam Reflectarrays for Ka-Band Applications

We present the modeling, design, and experiments of a class of low-profile and broadband dual-circularly polarized (DCP) reflectarrays (RAs) with independent beamforming for CP waves with opposite handedness. The proposed DCP RAs are comprised by an array of unit cells containing two cascaded anisotropic impedance surfaces backed by a ground plane. The DCP phase compensation offered by the RA cells is enabled by simultaneously utilizing cell rotation-induced Berry phase and dimension variation-induced dynamic phase. Numerical investigations of the diffraction properties of a linear gradient array of the DCP cells reveal that the designed cells can offer independent and high-efficiency deflection of CP waves with opposite handedness over a bandwidth of about 40%. Two Ka-band DCP RAs with a profile of only 0.16λ
₀
are demonstrated. The single-beam DCP RA achieves a measured peak gain of higher than 30 dBic with a joint 1 dB gain and axial ratio 0.5 dB bandwidth of around 30%, while the multibeam DCP RA exhibits a measured peak gain of about 26 dBic with a joint 1 dB gain and axial ratio 1.5 dB bandwidth of more than 25%. The demonstrated broadband DCP RAs are promising candidates for various wireless and satellite communication systems.