Design Method for Negative Refractive Index Metasurface Lenses by Using a One-Dimensional Distributed Transmission-Line Model

A design method for negative refractive index (NRI) metasurface lenses whose thickness is thinner than that of conventional NRI metamaterial ones is presented. A one-dimensional distributed transmission-line model is introduced to the design and the design formulas for determining the line length and the characteristic impedance are shown. As an example, a NRI metasurface lens operating at 1.85 GHz is designed based on the proposed method. A circuit simulation is carried out and complex voltage distributions are calculated to confirm the focusing operation of the designed lens whose thickness is sufficiently thinner than the wavelength.