Near-perfect tunneling and amplification of evanescent electromagnetic waves in a waveguide filled by a metamaterial: Theory and experiments

Abstract

Amplification of evanescent electromagnetic waves by a metamaterial slab is still a controversial issue. Metallic waveguides operating in cutoff provide a unique physical environment to produce and study these waves because isolated evanescent modes can be excited in such environment. In this paper, the tunneling of electromagnetic waves through a rectangular waveguide partially filled by a metamaterial is analyzed. Enhanced tunneling due to the amplification of evanescent waves in the metamaterial filled waveguide section is demonstrated. Since evanescent modes in rectangular waveguides are the superposition of two plane waves, the aforementioned results also show the amplification and tunneling of evanescent plane waves by a metamaterial slab in free space