A simple structure comprising a metal mesh, symmetrically surrounded by subwavelength
thickness dielectric layers, is shown to give near total microwave transmission over a broad
frequency range. The mesh may be considered to be a tunnel barrier since it behaves as an
ideal plasmonic metamaterial with a negative effective permittivity and no loss. The
introduction of the mesh into the dielectric cavity imposes a finite gradient on the
electromagnetic fields at the two mesh-dielectric interfaces. This defines a finite wavelength …