We propose a high refractive index metamaterial (HRIM)that is composed of two identical patch arrays symmetrically etched on both sides of a dielectric plate. By reducing the gap of adjacent patches and the thickness of dielectric plate, the proposed metamaterial can suppress the diamagnetic response and enhance the capacitance coupling, so that the refractive index of the metamaterial is higher than 10 in wideband from 4 to 8 GHz. Attributing to the property of high refractive index, the metamaterial can effectively improve the performance of a microstrip antenna when it is loaded as a superstrate. The measured results reveal that the antenna has an impedance bandwidth (S₁₁ < −10 dB) of 690 MHz (12.4%) and a maximum gain of 13 dB appearing at 5.6 GHz. The 1 dB and 3 dB gain bandwidths are 380 MHz (6.7%) and 590 MHz (10.3%), respectively. Fortunately, the profile of the antenna is only 0.19λ₀ (λ₀is the free space wavelength at central frequency). Furthermore, the profile can be further reduced to 0.15λ₀ when the radiation patch of the antenna is surrounded by another metamaterial.

我们提出了一种高折射率超材料（HRIM），该材料由在电介质板的两侧对称蚀刻的两个相同的贴片阵列组成。通过减小相邻贴片的间隙和介电板的厚度，所提出的超材料可以抑制反磁响应并增强电容耦合，从而使超材料的折射率在4至8 GHz的宽带范围内高于10。归因于高折射率的特性，当超材料被用作覆层时，其可以有效地改善微带天线的性能。测量结果表明，天线具有阻抗带宽（S ₁₁<-10 dB）690 MHz（12.4％），最大增益13 dB在5.6 GHz处出现。1 dB和3 dB的增益带宽分别为380 MHz（6.7％）和590 MHz（10.3％）。幸运的是，天线的轮廓仅是0.19λ ₀（λ ₀是在中心频率的自由空间波长）。此外，简档可以进一步减小到0.15λ ₀时的天线的辐射贴片被另一超材料所包围。