Metamaterial waveguide with reduced cross section

In this article, the use of a metamaterial walls is proposed for the design of waveguides with reduced cross section. First, the analytical modes expansion for cylindrical waveguides with anisotropic boundary condition is reminded. It will be shown that with particular anisotropic surface impedances on the waveguide walls, hybrid modes can propagate with a cut off frequency of the fundamental mode lower than the usual TE₁₁ mode in metallic waveguides. The design of the metamaterial surface is then presented with regard to its surface impedance properties. Finally, the dispersion properties of this waveguide with metamaterial walls are computed.