Novel Planar Meta-Structures with Anisotropic Left-Handed Properties

Two types of novel planar meta-structures with anisotropic left-handed properties are presented and behaviors of wave propagation in the structures are studied. Each of the structures consists of a two-dimensional periodic array of unit cells with metallic patterns on both sides of a dielectric substrate. The structures possess interesting anisotropic left-handed properties, which could be used in novel microwave device and antenna applications. Being a purely planar structure and not requiring any vertical metallic vias, the structures are advantageous in easy fabrication with high frequency scalability compared with bulky resonant type left-handed materials. Numerical simulations reveal that the proposed structures possesses anisotropic left-handed properties in which the phase and group velocities are anti-parallel in the orthogonal and diagonal directions of the Brillouin zone while they are not parallel in the other directions. The proposed two meta-structures have distinctive dispersion characteristics; one has dispersion characteristics of which the orthogonal left-handed frequency band is higher than the diagonal left-handed frequency bands, and the other has the opposite and more complex dispersion characteristics