A Broadband MIMO Antenna Based on Multimodes for 5G Smartphone Applications

In this letter, an eight-element broadband multiple-input-multiple-output (MIMO) antenna array with a simple structure based on multiple modes is presented, which covers 3.3-6 GHz for fifth-generation (5G) smartphone. Double coupled-fed loop modes and a slot mode are well excited by the feeding strip connecting with the tuning branch. The broadband antenna is well designed without loading any lumped elements, thanks to the tuning branch on the side frames. Furthermore, the polarization diversity technique is exploited to improve isolation. As a result, the MIMO system operates in the 3.3-6 GHz (S-11 < -6 dB) with desirable isolation higher than 12.1 dB, which satisfies the coverage of the 5G communication bands: n77/n78/n79 and 5G wireless local area network (WLAN). Besides, acceptable efficiency and envelope correlation coefficients of lower than 0.2 can also be obtained, which demonstrates that the presented MIMO array has potential for the mobile communication of 5G smartphones.