| With the continuous development of wireless communication technology,people's lives have undergone radical changes.Today,wireless communication has been fully integrated into people's lives,profoundly affecting people's food,clothing,housing and transportation.Today,the explosive growth of people's demand for data is forcing mobile communication technology to enter a new era.The fifth generation mobile communication technology(5G)is different from the previous first,second,third and fourth generation mobile communication technologies.5G will not only support data services for general users but also support industrial-level applications and driverless applications to achieve interconnection of all things.As one of the key technologies of 5G,Massive MIMO and large-scale multiple-input multiple-output technology have been the research hotspots in this field,and the implementation of multi-antenna system in mobile terminals is the hotspot.It is well known that mobile terminals are often small in size,and designing multiple antennas in a small headroom environment is a very challenging task.The size of the coupling between multiple antennas and the performance of the antenna system will directly affect the performance of mobile terminal communication,so it is of great research significance.Therefore,this thesis revolves around the use of new ideas and structures based on antenna multi-feed technology to achieve a high performance and low coupling 5G terminal multiantenna system.The main work of this thesis is as follows:1.The application of multi-fed antenna technology in a terminal environment is investigated.The multi antenna performance with the same effect is achieved by introducing multiple feeds and shorts on a single radiator with high isolation,low correlation and high efficiency between each feed port.Based on multi-feed MIMO antenna technology,two dual-band dual-feed MIMO antennas designed by using multi-feed technology are firstly introduced,both antennas support dual-band mobile communication bands and dual-band Wi Fi bands respectively,and dual-band operation mode is introduced in the antenna design by introducing branches at a reasonable location of the antenna,both antennas achieve a better decoupling effect while covering the required operating bands.After that,a larger scale MIMO antenna system based on multi-feed technology is designed,based on the preliminary results of the eight-feed MIMO antenna designed by multi-feed technology,parasitic branches and metal connecting line structure are introduced successively to solve the problem of insufficient isolation of some ports,and the result of the combination of the eightfeed MIMO antenna structure with the metal connection line structure and the ground choke slot structure can achieve the coverage of wide frequency band and the isolations among eight ports bigger than 15 d B.The above design well verifies that the multi-feed technology has the characteristics of simple structure,no additional circuit,good decoupling effect and high efficiency.2.Firstly,a curved metal rimmed dual-feed MIMO antenna working in 3.4?3.6GHz band is designed,and the decoupling principle of this antenna is analyzed,based on which the curved metal rimmed four-feed MIMO antenna is formed by the combination of two dual antenna units,in order to solve the problem of insufficient isolation between the two annular metal rims,a parasitic branch structure is introduced,and finally,based on the four-feed MIMO antenna,the curved metal rimmed eight-feed MIMO antenna is formed,and the overall isolation level of the eight-feed antenna is increased to more than 15 d B by adding choke slots in the middle of the eight-feed antenna ground,and finally the actual processing and testing results of the eight-feed MIMO antenna are given,and the testing results are basically consistent with the simulation results. |
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