未来无线通信系统的基站和移动终端均布局多个工作频率不同的Sub 6GHz MIMO天线组成的跨频段MIMO天线阵，以实现良好的广覆盖和深度覆盖，提高频谱利用率和数据率。设计移动终端Sub 6GHz跨频段MIMO天线阵，要实现宽带同频去耦，还需解决异频解耦、去辐射“遮挡”效应等新难题。本项目以无需额外滤波电路的滤波天线为切入点，从谐波抑制和辐射零点技术两方面展开研究天线和滤波的新型融合设计方法，实现天线的良好带外辐射抑制和频率选择性; 研究谐振模控制技术和滤波加载技术的最优组合，稳定滤波天线带内性能，实现天线宽带化和小型化；以滤波天线构造跨频段MIMO天线阵，通过磁电耦合二维协同实现宽带同频去耦，利用滤波天线的带外辐射抑制能力降低异频耦合。在此基础上，利用异频天线单元间相互垂直的极化及合理的排布方式降低异频单元间的 辐射“遮挡”效应，提高跨频段MIMO天线阵的性能，满足未来移动通信的要求。

Cross-band MIMO antenna array, which consists of several Sub 6GHz MIMO antennas with different operation bands, will be applied in both base stations and mobile terminals for future wireless communication systems to achieve the desired wide and deep coverage, and enhance the spectral efficiency and data rate. To design a Sub 6GHz cross-band MIMO antenna array for mobile terminal application, broadband co-frequency mutual coupling among the antenna elements with the same operation frequencies, should be weaken, and there are also several new technology problems need to be solved, such as reduction of cross-band mutual coupling among the antenna elements operating at different bands and elimination of radiation shielding. Based on the filtering antenna without additional filter circuit, in the project, the new fusion design method of antenna and filter is studied by doing more in-depth researches on harmonic suppression and radiation null technologies, simultaneously, so as to achieve a good filtering antenna response with high out-of-band radiation suppression level and good frequency selectivity. To stabilize the in-band performance of filtering antenna, the optimum combinations of the resonance-mode control method and the filter-loading method are studies, and the broad operation band and compact antenna size can be realized too. Cross-band Sub 6GHz MIMO antenna array is designed based on several kinds of filtering antenna elements having different operation bands, and the research on cooperation methodology of electromagnetic coupling will be carried out to realize the broadband co-frequency decoupling. The feature of out-of-band radiation suppression of the filtering antenna element is utilized to reduce the cross-band mutual coupling. Based on that, the reasonable arrangement for the antenna elements with different working frequencies and orthogonal polarizations is investigated to avoid the radiation shielding, leading to enhancement of the performance of the cross-band Sub 6GHz mobile terminal MIMO antenna array, and the requirements of the future wireless communication systems can be meet.