A Diplexer Based on the Spatial Filtering Property of Planar Anisotropic Transmission-Line Metamaterials

TLDR: In this paper, a planar anisotropic metamaterial was used to achieve frequency diplexing by exploiting the inherent spatial filtering property of the hyperbolic metammaterial.

Abstract: The objective of this work is to investigate the possible use of metamaterials to achieve frequency diplexing. The metamaterial of interest is a planar anisotropic metamaterial proposed by Balmain et al. in [1]. It was shown in [2] that this metamaterial is magnetically anisotropic and could be described by a diagonal permeability tensor. For a certain range of frequencies, two of the three diagonal elements of the permeability tensor become opposite in sign. Under this condition, plane-wave propagation is governed by a hyperbolic dispersion equation and the metamaterial could be referred to as a hyperbolic metamaterial [3]. As a result, under point-source excitation, resonance cones form as a consequence of the singularity associated with the characteristic surface of the hyperbolic dispersion equation. Since the resonance cone angle, which describes the direction of power flow [4], varies with the frequency of the propagating wave, the phenomenon may properly be termed “spatial filtering.” The diplexer presented in this work exploits this inherent spatial filtering property of the hyperbolic metamaterial to achieve frequency diplexing.