Linear-to-Circular Polarization Converter Based on Stacked Metasurfaces with Aperture Coupling Interlayer

In this paper, we propose stacked metasurfaces that can convert linearly polarized (LP) wave into circularly polarized (CP) wave. The metasurfaces consist of two layers of periodic subwavelength Jerusalem cross elements and one interlayer of periodic square rings. The anisotropic metasurface elements yield 90 degrees phase difference for two orthogonal linear polarizations upon transmission. The aperture coupling interlayer can provide a flat and close to unity magnitude response to improve the axial ratio (AR). A prototype of this metasurface polarization converter is simulated, fabricated and measured in Ku band. Both simulation and measurement results demonstrate good AR in the operating frequency band. This linear-to-circular polarization converter design can also be used in quasi-optical applications.