Planar double-negative metamaterial filters tunable by liquid crystals

This paper presents the concept of a double-negative metamaterial structure tunable by liquid crystal. A metamaterial unit cell consists of wires joined with split-ring resonators. Two configurations, employing liquid crystal as a tunable substrate, are proposed and discussed. Both models are defined in a way to take into account a practical realization of liquid crystal polarization. The concept is validated with electromagnetic simulations based on the finite-difference time-domain method, where scattering parameters are computed. Next, the effective refractive index is retrieved and tunability in both setups is compared.