Focusing millimetre waves by means of a permittivity-near zero narrow-waveguide lens

Abstract

An epsilon-near zero (ENZ) plano-concave lens is designed, numerically studied and experimentally demonstrated at millimeter-waves. The metallic lens is synthesized by an array of stacked narrow hollow rectangular waveguides working near cutoff emulating an ENZ medium. At the working frequency (f0 = 144 GHz, λ0 = 2.08 mm) the focusing properties of the lens demonstrate an experimental transmission power enhancement of 15.9 dB with a good impedance matching with free space.