Researches On High Isolated Antennas Applied To Massive MIMO

During the years when the development of wireless communication is becoming more and more high-speed,demand for rapid transmission rate and high channel capacity communication systems have an increasing impendency.While under the limit of strong interference and increasing shortage of spectrum resource,it's difficult to promote those we wanted.The Multiple Input Multiple Output(MIMO)technology,can obtain diversity gain and multiplexing gain by taking full advantage of multipath environment.Because of these properties,MIMO technology has the ability to improve channel capacity and transmission rates.Recently,massive MIMO(M-MIMO)is proposed,which introduces amounts of antennas to work for information transmission and reception,has the advantage of effectively improving the spectral efficiency and power efficiency.For reducing the impact of environmental disturbance furthest,and significantly improving communication quality,this thesis also adopts ultrawideband(UWB)technology,two multi-element MIMO antennas are proposed to be used in massive MIMO application.The main contents of the thesis are as follows:The first chapter mainly introduces decoupling ways of multi-antennas and recent progress,from backgrounds,methods of UWB MIMO to massive MIMO antennas,and development of massive MIMO to present our purpose and meaning of this thesis.The second chapter gives some important performance parameters in MIMO antenna design,which concludes envelope correlation coefficient(ECC),multiplexing efficiency(ME)and so on.The MIMO technology and UWB technology are given in detail.The third chapter proposes a two-port UWB MIMO antenna.The antenna includes two reversely installed monopoles,and an interdigital-like isolated structure is designed,which can decrease the coupling current between two ports availably.The results of simulation and measurement show that,the proposed antenna has a return loss higher than 10 dB and isolation higher than 20 dB at the frequency band from 3.8-11.8 GHz.At the same time,we have calculated the MIMO performance parameters,the results show that the antenna can achieve the envelope correlation coefficient lower than 0.3,multiplexing efficiency higher to 0.55,and mean effective gain(MEG)ratio lower than 3 dB.The fourth chapter designs a four-port dual-polarized UWB MIMO antenna.Four elements are placed orthogonally every two adjacent,and the grounds are connected together by isolation structure,which is a good way to decrease mutual coupling..Simulated and measured results indicate that,this four-port antenna has a reflection coefficient lower than-10 dB,and transmission coefficient lower than-15 dB at the frequency band from 2.1GHz to 8.5GHz.Maximum test efficiency and gain are higher to 75% and 8.5 dB.The fifth chapter verifies the feasibility that applies the four-element MIMO antenna in massive MIMO application.Two kinds of arrangement ways of M-MIMO design are simulated,the results prove that these two can obtain isolation higher than 15 dB and return loss higher than 10 dB at band of 2.4-9GHz.One array structure is measured,to prove the identical to simulation.The sixth chapter has a conclusion on the whole thesis.It proposes the insufficiency in current works,and has a discussion on the modified ways of later works.