Bi-functional meta-material for vortex beam generating with low RCS characteristics

Meta-material has been proved to be an effective method to manipulate wave ranging from microwave to optic spectrum. Here, we employ a metasurface, namely two-dimensional equivalent of meta-material, to design a vortex beam generator with low radar cross section (RCS) characteristic. An anisotropic meta-atom is firstly optimized to control reflection phases independently for orthogonally polarized waves in a broad bandwidth. Then various meta-atoms with different sizes are assembled into a whole prototype, which is not only capable of reducing the backward RCS for x-polarization but also generating vortex beam for y-polarization. Simulated results further verify the theoretical prediction, indicating polarization-dependent functions for orthogonally polarized waves. This bi-functional metasurface and its application for vortex beam generating and RCS reduction may promote the application of artificial electromagnetic meta-material. (paper)