Hyperbolic metamaterial platform for realization of efficient wideband directive antennas

Impedance matching and gain are among the most challenging antenna parameters to achieve in case of a broadband operation. Hyperbolic metamaterials, initially introduced for this purposes by optical community, can contribute to this endeavour. Here we propose and numerically analyse a new broadband directive antenna design, based on hyperbolic metamaterial slab with a patterned layer on top. Energy from a subwavelength coaxial cable port is shown to be efficiently harvested into bulk modes of the metamaterial over a broad frequency range. Highly localized propagating waves within the medium have a well-resolved spatial-temporal separation owing to the hyperbolic type of effective permeability tensor. This strong interplay between chromatic and modal dispersions enables routing different frequencies into different spatial locations within compact subwavelength geometry. An array of non-overlapping resonant elements is placed on the metamaterial layer and provides a superior matching of localized electromagnetic energy to the free space radiation.