Dual-band epsilon-negative (ENG) transmission line metamaterials based on microstrip lines loaded with pairs of coupled complementary split ring resonators (CSRRs): Modeling, analysis and applications

Abstract

Microstrip lines loaded with pairs of electrically coupled complementary split ring resonators (CSRRs) are studied for the first time. For the general asymmetric case, where the line is loaded with different CSRRs at each stage (pair), the structure exhibits negative effective permittivity in the vicinity of two different frequencies, i.e., it behaves as a dual-band epsilon-negative (ENG) transmission line metamaterial. A lumped element equivalent circuit model of the unit cell of these artificial lines, that includes the electric coupling between the CSRRs forming the pair, is proposed. This model is analyzed in detail and the equation that provides the transmission zero frequencies is derived. Finally, the model is validated by comparing electromagnetic simulation and experimental data to circuit simulations with extracted parameters. These structures may be applied to the design of stop band filters, including dual-band notched filters, and sensors based on frequency splitting.