A dual-CP reflectarray unit cell for realizing independently controlled beams for space applications

The paper presents a dual circular polarization unit cell for realizing a reflectarray that synthesizes two independent patterns based on the polarization of the incident field. To this end, a thin polarizer, which converts incident circularly polarized (CP) waves into orthogonal linearly polarized (LP) waves, is cascaded with a dual-linear-polarization (DLP) reflectarray. The reflectarray then applies the required reflection phases to the LP waves. The proposed antenna system is structured by placing the polarizer adjacent to the DLP reflectarray. Numerical simulations are arranged to assess the performance and ability of a 20 GHz unit cell design in providing high polarization purity and independent reflection phases for orthogonal CP waves. Enclosing 4×4 polarizer cells as small as 0.14λ×0.14λ, the unit cell features an overall thickness of ~1λ and lateral dimensions of 0.55λ×0.55λ.