High-directivity antenna using reconfigurable near-zero index metamaterial superstrates

The near-zero refractive index metamaterials (ZIM) have attracted more and more attentions because of their novel properties. In this paper, a theoretical analysis of a patch antenna with different ZIM superstrates has been given, which gives an insight into the mechanism of directivity enhancement using three different ZIM metamaterials as the antenna´s superstrates. It shows that double near-zero (permittivity and permeability are near zero, DNZ) metamaterial superstrate can converge the aperture E-field and H-field of the antenna simultaneously. The increase of 9.2dB of radiation directivity can be obtained.