In this paper, we propose a zero-refractive index metamaterial (ZIM) with a simple structure, which is composed of dielectric spheres. The effective medium theory was used to invert the equivalent electromagnetic parameters of metamaterials. Metamaterials have nearly zero refractive index in the three bands of 17.96–19.46 GHz, 22.36–23.16 GHz and 23.68–24.32 GHz, respectively. Through monitoring the electric field and phase distribution at three zero frequencies, the zero refractive index characteristic is verified. Based on the proposed ZIM, a three-dimensional polarization-independent invisibility cloak within three wavebands was designed and numerically demonstrated.

在本文中，我们提出了一种结构简单的零折射率超材料（ZIM），它由介电球组成。有效介质理论被用来反演超材料的等效电磁参数。超材料在 17.96-19.46 GHz、22.36-23.16 GHz 和 23.68-24.32 GHz 三个频段中的折射率几乎为零。通过监测三个零频率处的电场和相位分布，验证了零折射率特性。基于所提出的 ZIM，设计了一种在三个波段内与偏振无关的三维隐形斗篷，并进行了数值演示。