A multi-band multi-antenna system has become an important trend in the development of mobile communication systems. However, strong mutual coupling tends to occur between antenna elements with a small space, distorting array antennas’ performance. Therefore, in the multiple-input multiple-output (MIMO) antenna system, high isolation based on miniaturization of the antenna array has been pursued. We study in depth the methods of decoupling between antenna elements. Reasons for the existence of mutual coupling and advantages of mutual coupling reduction are analyzed. Then the decoupling methods proposed in recent works are compared and analyzed. Finally, we propose a metasurface consisting of double-layer short wires, which can be applied to improve the port isolation of antennas arranged along the H-plane and E-plane. Results show that the proposed metasurface has good decoupling effect on a closely placed antenna array.

多频带多天线系统已经成为移动通信系统发展中的重要趋势。但是，在空间小的天线元件之间容易发生强的相互耦合，从而使阵列天线的性能失真。因此，在多输入多输出（MIMO）天线系统中，已经寻求基于天线阵列的小型化的高隔离度。我们深入研究了天线元件之间去耦的方法。分析了存在相互耦合的原因以及相互耦合减少的优点。然后对最近提出的解耦方法进行了比较和分析。最后，我们提出了由双层短线组成的超颖表面，可将其应用于改善沿H平面和E平面布置的天线的端口隔离。