Controlled leaky wave radiation from anisotropic epsilon near zero metamaterials

We investigate the emission of electromagnetic waves from biaxial subwavelength metamaterials. For anisotropic structures that exhibit a vanishing dielectric response along the longitudinal axis and possess a tunable transverse dielectric response, we find remarkable variation in the launch angles of energy associated with the emission of leaky wave radiation. We write closed-form expressions for the energy transport velocity and corresponding radiation angle φ, defining the cone of radiation emission, as functions both of frequency and of material and geometrical parameters. Full wave simulations exemplify the broad range of directivity that can be achieved in these structures.