Antenna matching in ε-near-zero metamaterial channels

Here we explore the matching properties of coaxial cables in ultranarrow channels filled with zero permittivity metamaterials. We discuss how the anomalous properties of such channels may allow a simple matching design, valid for arbitrary waveguides, with large degrees of freedom in terms of geometry, length and possible bending of the connecting channel. Moreover, the static-like properties of the channel may allow complete matching, independent of the relative position of the antenna inside the channel. We propose a simple verification of these concepts in rectangular channels operating at cut-off, which realize a simple and powerful mechanism for achieving effective permittivity near zero in this geometry. Our findings may constitute an elegant and powerful method for matching coaxial antennas to waveguides of arbitrary shape and geometry.