| With the full implementation of 5G communication systems,the demand for base stations and mobile terminal antennas with high-performance and miniaturized is increasing.It is well known that at least 6-8 antenna elements need to be integrated in a 5G mobile terminal to provide good diversity gain and multiplexing for meeting the high rate requirements of the 5G system.However,more units will inevitably cause mutual coupling between units and reduce the performance of the antenna system.This is a difficulty for the MIMO antenna design of 5G terminals,also a current research hotspot.In addition,as a combination of technology and fashion,smartphones have been evolving toward a thinner,higher-screen design concept.How to lay out more antenna units inside a full-screen mobile phone with a very small clearance area and compatible with the 5G frequency band in various regions of the world is a great challenge for antenna design.Therefore,it is of great practical significance to study a compact,multi-band MIMO antenna for 5G terminal equipment.This paper studies and analyzes the compact multi-band MIMO antenna for 5G mobile terminals.First,this paper investigates various 5G antenna arrays used in smart phones,analyzing the advantages and disadvantages of various designs,and summarizes the difficulties of current 5G antenna array design.Moveover,introduces the key theory of mobile phone MIMO,discusses how to realize wideband,miniaturization and decoupling between MIMO mobile phone antennas.Then,this paper proposes a compact multi-band 12 port MIMO antenna based on orthogonal layout.The antenna operates in the LTE band 42/43(3400-3800 MHz)and LTE band 46(5150-5925 MHz)bands.It uses a coupled feed antenna and a mid-end open slot antenna.Both antennas are very compact and the required clearance area is small.The antenna area is 631 mm~2,of which the system board area is only 192 mm~2,and the required clearance area for radiation is 123 mm~2.Decoupling is achieved by orthogonal layout between the two antenna elements,which improves the isolation of the MIMO system.The measured data shows that the compact multi-band antenna has good antenna performance and MIMO characteristics,and compatible with 5G frequency band in various regions of the world.Finally,a multi-band 16-port MIMO antenna based on coupled loop type is proposed.The array covers LTE band 42/43 and LTE band 46 in the form of a coupled loop antenna pair.Antenna is based on the principle of the coupled antenna,in which the feeder branch and the short-circuit branch are coupled to reduce the resonant length of the antenna and realize a wide frequency domain.Compared to the previous chapter,the antenna area and required clearance area of this chapter are reduced by 327 mm~2 and 19 mm~2,respectively.The measured performance of antenna and MIMO is excellent.The average channel capacity of the high and low frequency is 35.6 bps/Hz and 36 bps/Hz,respectively,which is 0.5 bps/Hz higher than the antenna array proposed in the previous section. |
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