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A Negative-Refractive-Index Metamaterial for Incident Plane Waves of Arbitrary Polarization

In this letter, a left-handed artificial dielectric is proposed. Using resonating broadside coupled patches to generate a negative permeability and thin strips to generate negative permittivity, a negative index of refraction that is matched to free space can be designed. The structure is fabricated from a single dielectric sheet printed on both sides by metal patterns that couple to externally incident plane waves of any linear polarization. Unlike many previously published structures, the waves interact through perpendicular incidence to the surface. An experiment was carried out at 10 GHz to verify the left-handed behavior with an extracted index of refraction of -1.04 matched to free-space with 26.0 dB return loss and 0.77 dB insertion loss. A multilayer version was also designed that achieved fractional dispersion bandwidths comparable to those of transmission-line implementations