Research On Key Technologies Of LTE And Sub-6G MIMO Antennas For 5G Mobile Terminal Applications

With the development of the information technology,smart devices for mobile terminals have gradually evolved from fourth-generation mobile communication technology(4G)to fifth-generation mobile communication technology(5G),with larger transmission rates,higher reliability and greater throughput.Mobile communication technology has become the key to mass mobile communication in the future.Therefore,as the main carrier of future mobile terminals,mobile phone terminals have higher requirements for the performance of mobile phone antennas.At present,Multiple-Input Multiple-Output(MIMO)technology,as a vital technology in the field of wireless communication,has improved the capacity of wireless channels,spectrum utilization and unique advantages of data transfer rate.Therefore,supporting multiple-input multiple-output antennas is the research focus of commercial 5G in the sub-6 GHz frequency band(sub-6 GHz).However,sub-6 GHz MIMO antennas still need to be miniaturized,multi-band and highly isolated.This paper summarizes and researches various technical methods such as miniaturization,multi-band,decoupling of mobile phone terminal antennas and designs two mobile phone terminal MIMO antenna systems.The main contributions of this paper are listed in below:Firstly,a wideband LTE 4 × 4 MIMO antenna is designed for mobile phone terminals.This MIMO antenna array works at 700-960 MHz(2 × 2 MIMO)and 1710-2690 MHz(4 × 4 MIMO).The RF switch is used to switch the inductance at the antenna grounding branch to adjust the resonance frequency point,which can effectively cover all the desired frequency bands.The reasonable selection and placement of IFA and LOOP antennas makes the isolation over 11 d B.This antenna has small clearance,wide bandwidth,excellent radiation efficiency and good MIMO performance,which has great potential for future 5G communication applications.Secondly,this paper designs a sub-6 GHz 5G MIMO antenna system for mobile phones,including 8 element MIMO antennas with dual-band and highisolation.The innovation of this design lies in the reasonable usage of LOOP with dual resonant modes,0.5? and 1?,respectively.The 1? mode is a balanced mode(naturally high isolation)working at higher frequency,the 0.5? mode works at lower frequency and its isolation with other antennas is improved by the neutralization line decoupling technology.As a result,this 8-element MIMO antenna system achieves multiple bands,high isolation and excellent MIMO performance,which could be applied to future 5G mobile phone terminals.