Fabrication and characterization of a negative-refractive-index composite metamaterial

We have designed, produced, and experimentally characterized 2.7 mm thick composite panels having negative refractive index between 8.4 and 9.2 GHz. The composite metamaterial is fabricated using conventional commercial multilayer circuit-board lithography; three-dimensional physical (as opposed to electromagnetic) structure is introduced by the use of vias to form sections of the scattering elements in the direction perpendicular to the circuit board surfaces. From scattering parameter measurements, we show that the complex permittivity, permeability, index, and impedance of the composite can be unambiguously determined. The measurements enable the quantitative determination of the negative index band and associated losses. The extracted material parameters are shown to be in excellent agreement with simulation results.