High transmission of negative permittivity materials based on strong magnetic field coupling

Materials with negative permittivity are opaque for electromagnetic wave such that the transmitted signal cannot travel through them. To combat this phenomenon, we propose a novel high transmission mechanism using periodic placed split-ring resonators and metallic wires to construct a transparent sandwich structure. This structure consists of three layers of materials, where the material with negative permittivity is sandwiched between the materials with high permittivity. With the given frequency, we firstly exploit the metallic wires and split-ring resonators to attain non-transparent negative permittivity and high permittivity, respectively. By effective medium theory, effective relative permittivity retrieved from these materials’ S parameters is verified to be negative or high. Then a resonant tunneling of electromagnetic fields occurs in the proposed three-layer sandwich structure. Simulated and measured results show that this structure fulfills high transmission, although each single material layer is nearly opaque. In addition, this high transmission mechanism is characterized by strong magnetic field coupling and an optimized coupling distance. The high transmission phenomenon and resonant tunneling mechanism provide an idea of reference to realize perfect transmission through opaque materials, which is also realizable in infrared or optical regimes with appropriate designs.