Electromagnetic wave transmission through subwavelength metallic meshes sandwiched between split rings

We report the extraordinary enhanced transmission of microwaves through a subwavelength metallic mesh sandwiched between two identical split-ring arrays. Such split-rings/metallic mesh/split-rings structure demonstrates some unique electromagnetic (EM) characteristics. It is found that the transmittances of EM wave are significantly enhanced at some frequencies near the stop bands of the split rings. The theoretical simulation indicates that two different physical mechanisms dominate those transmissions: negative refractive index effect and electromagnetic wave tunneling when EM wave penetrates through negative permittivity media sandwiched between two high permittivity slabs. (C) 2005 American Institute of Physics.