Demonstration of enhanced broadband unidirectional electromagnetic radiation enabled by a subwavelength profile leaky anisotropic zero-index metamaterial coating

In this paper, we report a technique for creating broadband unidirectional electromagnetic radiation with a grounded nonmagnetic anisotropic zero-index metamaterial coating. We demonstrate that the leaky modes supported by the finite sized coating structure can be exploited to create a unidirectional radiation device with a subwavelength thickness of only 0.12{λ}. Numerical simulations and experimental characterization of the metamaterial-enabled radiator confirm the physical mechanisms governing its performance, showing a stable directive beam with an over fivefold radiation power enhancement at broadside. Due to the resulting nonmagnetic material properties, this approach provides a new path to highly efficient, small footprint, low profile, and broadband directive radiation devices for microwave and potentially even optical wavelength applications.