Metamaterial-based feed antenna with dual-polarized elliptical radiation beam

A feed antenna with elliptical radiation beam is proposed in this paper. The designed feed antenna has a rectangular radiation aperture, and metamaterial layer with low relative permittivity (∊ L < 1) is coated on the inner boundary of the feed. It is shown that the metamaterial layer can help to achieve similar elliptical radiation patterns for both the horizontal polarization and the vertical polarization. The characteristic modes supported by the feed antenna are derived to explain the mechanism of the dual-polarized elliptical radiation patterns.