Broadband Metamaterial-Enabled Hybrid-Mode Horn Antennas

In this paper, we show a broadband metasurface satisfying the balanced hybrid condition and its use as a liner to implement hybrid-mode horns. The design approach combines a nature-inspired optimization technique and an efficient full-wave electromagnetic solver, making it possible to realize metamaterials or metasurfaces with customized dispersive properties. With regard to surface impedances, the metasurface is found to be equivalent to a homogeneous metamaterial slab backed by a PEC ground plane. Therefore, we will consider the results of a numerical study of a conical horn antenna with a homogeneous metamaterial liner. The far-field radiation patterns and aperture field distribution confirm hybrid-mode operation over a wide bandwidth, validating the metasurface design methodology.