Miniaturized resonant inclusions as non-bianisotropic double negative metamaterials for normal incidence

Two novel resonators were devised which are amendments on commonly used S-shaped resonator and enable a great miniaturization rate. The symmetrical structure of these inclusions can avoid magnetoelectric coupling in the artificial constituents that preclude the bianisotropy. One of these metamaterials is an integration of continuous wire and an S-shaped-spiral. The other is a structure of SRRs and S-shape resonator with improved electromagnetic coupling and reduced electrical size. Both of them have wide negative refraction passband with low losses. The superior performances of these structures were investigated numerically and experimentally for only normal incidence case and tested through a proper comparison with the S-shaped resonator.