Cylindrical Metasurface-Cladded Waveguide Filled With Positive- or Negative-Epsilon Dielectric

This work proposes a metasurface-cladded waveguide which may be filled with positive- or negative-epsilon materials. This design targets microwave plasma technology, particularly devices intended to be loaded with tenuous and dense plasma. Namely, the dielectric permittivity of the filling material is positive or negative, depending on the scenario. First, a theoretical model has been proposed to assess the electromagnetic propagation regime. Specifically, the cladding metasurface is treated as an anisotropic surface impedance imposed at the edge of the waveguide. Second, a possible design relying on a hollow dielectric substrate whose internal surface is coated with a lattice of metallic patches is numerically investigated. The results show that the waveguide propagates electromagnetic waves independently from the sign of the dielectric permittivity of the filling material. The latter parameter and the geometry of the metallic lattice are shown to be governing design parameters, in particular, in determining the cut-off frequency of the fundamental mode.