基于超材料的低互耦MIMO天线设计

Design of low mutual coupling MIMO antenna based on metamaterials

为了降低多输入多输出(multiple-input multiple-output,MIMO)天线不同单元之间的耦合,设计出一种螺旋状磁负超材料单元。通过MATLAB软件提取该超材料单元的本征参数,验证了其磁负特性。然后根据所设计超材料单元在磁负频段产生阻带这一特性,设计一个中心频率为3 GHz的二单元MIMO天线。通过将超材料加载于MIMO天线的两个辐射贴片之间,使中心频率处的天线单元互耦有效缩减至-37.8 dB,且整个工作频段范围内的耦合系数S21均在-28 dB以下。另外,超材料的加载并没有破坏天线的阻抗匹配特性及远场辐射特性,且天线单元间距仅为5.2 mm。因此,所设计的磁负超材料单元可用于设计紧凑型MIMO天线。

In order to diminish the coupling between the different elements of the multiple-input multiple-output(MIMO)antenna,a spiral-shaped magnetic negative metamaterial element is designed.The intrinsic parameter of the metamaterial unit are extracted by MATLAB software,which effectively verifies its magnetic negative characteristics.Then,according to the characteristics of the designed metamaterial unit that produces a stop band in the negative magnetic band,a two-element MIMO antenna with a center frequency of 3 GHz is designed.By loading the metamaterial between the two radiating patches of the MIMO antenna,the mutual coupling of the antenna unit at the center frequency is effectively reduced to -37.8 dB,and the coupling coefficient S21 in the entire working frequency range is below -28 dB.Furthermore,the loading of metamaterials does not damage the impedance matching characteristics and far-field radiation characteristics of the antenna,and the distance between antenna elements is only 5.2 mm.Therefore,the designed magnetic negative metamaterial unit can be used to design a compact MIMO antenna.