Orthogonal-polarized MIMO Antennas Designed For 5G Smart Terminals

As the 4G/4G+(the 4th Generation mobile communication)is fast developing and becoming mature,many countries and organizations have shifted their focus of research to the future 5G communication(the 5th Generation mobile communication).Although the global uniform standards for 5G system haven’t been set hitherto,the demands for increasingly diversified usage scenarios and high quality wireless communication services of the users have revealed the trend of 5G evolution.In the 5G communication,peak data rate,user experienced data rate,spectrum efficiency and some new indicators will be significantly improved.Undoubtedly,this will make high requirements for smart terminal antenna designs.MIMO(Multi-Input Multi-Output)technology can enhance the system channel capacity without consuming additional spectrum.However,it is still a great challenge that how to integrate more antenna units into the very limited space in a smart terminal.To solve the problem,this paper proposes that adopting orthogonal polarization technique to realize good isolation between antenna units under a compact antenna arrangement so as to enhance the system channel capacity.Firstly,combining with the current research progresses of 5G communications in countries,this paper analyzes and discusses the potential developing direction and key technical indicators for future 5G communication.Then,towards these indicators,the difficulties existed in antenna design are analyzed,and the corresponding solutions and their problems are discussed in this paper.Secondly,an 8-port dual-polarized MIMO antenna using loop structures for 5G smartphone is introduced in Chapter Three.This antenna is based on a microstrip antenna;by orthogonally coupled feeding at its adjacent edges,dual polarization can be obtained.Without any demands for ground clearance,this antenna can go with the designing tide of "full screen".The measured results verified the feasibility of "using the orthogonal polarization technology to realize more-antenna arrangements in smart terminals so as to get higher channel capacity".Then,another dual-polarized hybrid 8-antenna array for 5G smartphone application is presented in Chapter Four.By the strategical use of different radiating mechanisms,this scheme employs coupled fed straight-dipole and open-end slot antenna with parallel arrangement to get orthogonal polarization features.With these features,the antenna performances are able to be guaranteed.Finally,in order to improve the space utilization,so as to realize more-antenna arrangements and higher channel capacity,a 12-port orthogonally tri-polarized MIMO antenna array based on a tri-polarization module is proposed in Chapter Five.This tri-polarization module can achieve a three-antenna arrangement in a very compact space and guarantee the port isolations.The measured results show that the channel capacity of the proposed 12-port MIMO antenna is about 5 times higher than the upper limit for a 2×2 MIMO system,which is very promising in future 5G communication.