A waveguide and a communication system including the waveguide are described. The waveguide is configured to propagate an electromagnetic wave having an operating frequency along the waveguide. The waveguide includes a substrate having a first dielectric constant, and an array of spaced apart unit cells at least partially embedded in the substrate and arranged along the waveguide. Each of a plurality of the unit cells in the array of spaced apart unit cells has a first transmission parameter S121 having a lowest resonant frequency Γ1 and includes a dielectric body and one or more electrically conductive layers disposed on and partially covering the dielectric body. The dielectric body has a second dielectric constant greater than the first dielectric constant at the operating frequency and has a second transmission parameter S221 having a lowest resonant frequency Γ2 greater than Γ1.