Study Of 5G Mobile Terminal Antennas

With the wide application of mobile communication technology,the current 4G/LTE cellular system can not meet the requirements of transmission rate,latency and coverage of future massive data any longer.Thus,the fifth generation mobile communication technology(5G)came into being.By increasing the number of antenna units,MIMO technology can improve the signal transmission rate,which is suitable for 5G microwave band.Therefore,two 8-element MIMO antennas are designed for future 5G smartphones,and a broadband dual-polarized antenna is designed for 5G terminals.The contents this paper is arranged as follows:Firstly,the development of mobile communication technology is introduced;the element form and decoupling technology of terminal MIMO arrays are summarized;several parameters for evaluating the performance of MIMO system are introduced.Secondly,we provide two 8-element MIMO arrays for smartphone application.In both designs,all array units are printed along two long side frames of the smartphone,which reserve a full ground plane for 2G/3G/4G antennas design and is applicable for massive MIMO configuration,to take multi-band operation into consideration,a dual-band antenna array is formed for various wireless communication services and full use of limited space in smartphone;for the one with neutralized line,good reflection coefficients of better than –6 dB and acceptable isolations of better than 11.5 dB are achieved.The total efficiency for each antenna element is better than 40% for LB(3.5-GHz)and HB(5-GHz).In addition to that,the proposed antenna array has also shown desirable MIMO performances with ECC lower than 0.08 and ergodic channel capacities of approximately 37.5 bps/Hz and 38.5 bps/Hz in the LB and HB,respectively;for the one with wavetrap decoupling resonator,acceptable isolations of better than 12.5 dB is achieved,the proposed antenna array has also shown desirable MIMO performances with ECC lower than 0.12 and ergodic channel capacities of approximately 39.5 bps/Hz and 40 bps/Hz in the LB and HB,respectively,the hand phantom effects are also investigated,and the results show that the proposed 8-antenna MIMO array is a promising candidate for future 5G smartphone applications.Lastly,a broadband cross-polarized antenna for terminal use is proposed,which can support 2G,3G,4G and 5G Sub-6 GHz bands simultaneously.In order to make full use of the given dimension,the dipole branches are set in a step shape to produce low-frequency resonance;to reduce the overall profile of the antenna,the feeding structure is realized by unbalanced microstrip;besides,coupling method is adopted to generate resonance in 5G band.Acceptable reflection coefficients and good isolations of better are achieved,the over all efficiency are all better than 43%,these results show that the antenna structure is suitable for future terminals with 5G band.