Research On MIMO Antennas For 5G Mobile Terminals

In Recent years,4G(the 4^thGeneration mobile communication)experienced rapid development and has now matured.5G(the 5^th Generation mobile communication)is now drawing more attention of various countries.In 5G era,the peak date rate and spectrum efficiency will be greatly improved.MIMO(Multi-Input Multi-Output)technology can enhance the channel capacity of the system and become one of the core technologies for 5G operation,the 2×2 MIMO antenna for 4G has already been commercialized in mobile handsets,however,dual-port system is still incompetent for 5G,because 5G is predicted to possess an aggregate date rate.Since this,design a MIMO system with more antenna units and lower coupling in a limited space is a challenging task for5G terminal antenna design.The research goal of this thesis is to design MIMO systems with good isolation and radiation performance under a compact antenna arrangement so as to enhance the system channel capacity.Firstly,this thesis briefly explained the theory of MIMO system and its evaluation parameters.Then discussed the potential developing direction and key technical indicators for 5G communication mobile terminals MIMO antenna,which lays the foundation for subsequent research work.Then this thesis introduced a 6-port dual-band MIMO antenna array based on orthogonal polarization technique.The antenna unit is a T-shape slot antenna which have no requirements on the clearance area.By using slot antenna's radiating mechanism,put them orthogonally around the corner to get orthogonal polarization so that the low mutual coupling can be get without using any additional decoupling structures.The proposed structure has been fabricated and measured.The results verified this MIMO antenna can operate during 3.4-3.6GHz&4.8-4.9GHz,in working bands,the coupling between any two ports can be very low,and the ECC between any two ports is less than 0.1.Also,omnidirectional radiation performance can be guaranteed.Subsequently,a 12-port dual-band MIMO antenna array has been proposed.The antenna unit of this system is a monopole antenna based on double-sided dual-strip,the operating bands can cover the major operators of 5G.By using the characteristics of the antenna's structure and put them along the tow long sides,then introduced defective ground structure which improve the isolation by 7d B.The stimulated results of this compact MIMO system show that the isolation between any two ports can achive14d B,and the ECC is less than 0.15,also the antenna unit has good radiation performance.This structure is a suitable choice for terminal equipment in future 5G communication.