Equivalent circuit extraction of the double-fishnet metamaterial based on its electrodynamics

In this work, an equivalent circuit for the double-fishnet metamaterial is proposed. The extraordinary transmission (ET) through each of the two layers of subwavelenth holes is modeled as two LC parallel tanks. Another LC parallel tank put in series with the previous two, models the mutual inductance and capacitance between the layers, also associated with the ET and the higher order modes. All lumped elements are extracted from a full inspection of the electromagnetic fields at the most relevant frequencies. The effective index of refraction and the scattering parameters obtained with the equivalent circuit matches remarkably the one obtained from full-wave numerical calculations.