MIMO Antenna Design And Performance Research In 4G Mobile Communication

With the increase of transmission rate and communication quality,the problems of spectrum resource scarcity and multipath fading become more and more serious,MIMO system can make full use of space resources,effectively improve the transmission rate and spectrum utilization.With the mobile phone development trends of more and more ultra-thin and intelligent,mobile phones and other mobile terminals leave smaller space for antenna,and 4G network to be compatible with 2G,3G network,which requires MIMO antenna not only need small size but also with a wide frequency band.At the same time,the metal borders seriously affect the impedance matching and radiation performance of internal handset antenna,which greatly increased difficulty of designing MIMO terminal antenna.In this paper,the several designs of miniaturized and broadband antennas are analyzed in detail.On this basis,three MIMO antenna design schemes are proposed for mobile phone.First of all,a multi-band handset MIMO antenna with a hybrid decoupling structure is presented.The antenna consists of a coupled loop antenna and a coupled monopole antenna,and the mixed decoupling network which is composed of the neutral line and the floor block greatly improves the isolation of the MIMO system.The antenna structure is simple,compact,and easy to process.Then,a design scheme for metal frame intelligent machine MIMO antenna based loop antenna is presented.The metal frame is divided into four parts,coupling feeded by the inverted L-type feedline and the resonants are generated in the low frequency band and the high frequency band,respectively.The internal antenna and metal frame cover the WWAN/LTE frequency band together.The two antennas located in two corners of the system substrate,to achieve a good isolation.Finally,a MIMO antenna for a metal frame handset based on monopole antenna is presented.The antenna is composed of metal frame and curved Monopole antenna.The metal frame has a resonant point in the low frequency band by monopole coupling.Monopole antenna and the high order resonant point of the frame covers the high frequency band of the antenna.The isolation of the MIMO system is obviously improved by loading the bent slot on the floor.In this paper,the feasibility of the proposed three design schemes is verified.The test results show that the three antennas can meet the requirements of the bandwidth,isolation and the radiation performance.To analyze the interaction between the antenna and the human body,two of the antennas were simulated by hand and head model.The results show that the antenna performance is stable and the value of SAR is low,which meet the actual engineering requirements.