An anisotropic metamaterial-based rectangular resonant cavity

Resonance properties of a rectangular resonant cavity filled with an anisotropic metamaterial bilayer are investigated. Different from the isotropic case and the one-dimensional resonator, the resonance properties in such a cavity are closely related to the dispersion relation of the anisotropic medium. Three cases including six subcases of different combinations of metamaterials are discussed and it is found that subwavelength resonance modes may occur in all subcases. Particularly, the relation between resonance modes and the transverse cavity width is investigated, and calculated results show that there are infinite subwavelength resonance modes as the transverse cavity width approaches zero. Requirements of the material and geometry parameters to construct a subwavelength resonant cavity are revealed by theoretical analysis, which demonstrates that this kind of subwavelength resonator brings more design flexibility and tolerance.