Polarization independent isotropic near-zero-index metamaterials composed of dielectric spheres for 3-D invisibility cloaks

Polarization independent isotropic near-zero-index metamaterials composed of dielectric spheres are presented. The constitutive parameters and the dispersion characteristics are obtained by full-wave simulations. It is shown that, with dielectric spheres of radius 1.5 mm and dielectric constant of 34, the medium exhibits a near-zero-index with little phase distributions at 24.53 GHz. In addition, 3-D invisibility cloaks are numerically demonstrated using the proposed near-zero-index metamaterials regardless of the cloaked materials.