Research On The Decoupling Technology Of Miniaturized MIMO Antenna

With the vigorous development of wireless communication technology and the explosive growth of mobile communication users,how to improve communication capacity and communication reliability has become the primary problem to be solved in the development of communication technology.Multiple Input Multiple output(MIMO)technology,that is,multi-antenna technology,can make full use of space wireless resources and play an extremely important role in improving spectrum efficiency and data transmission reliability.However,with the development of portable devices and miniaturization of mobile terminal devices,the space reserved for multiple antennas in mobile terminal devices will be very limited,and the multiple antennas placed in limited space will have a strong electromagnetic coupling phenomenon.The strong mutual coupling will change the amplitude and phase distribution of the current on the adjacent elements of the antenna,and then affect the performance of the antenna.Therefore,the decoupling of miniaturized multi-antennas is studied in this paper.In this paper,the miniaturization technology of antenna unit,wideband technique and decoupling technology of multi-antenna are studied,which provides a theoretical basis for the design of MIMO antenna.The main work of this paper is as follows:Firstly,a miniaturized UWB MIMO antenna with high port isolation is designed.The antenna is miniaturized by slotted radiating patch and floor,and the radiation patch unit is elliptical disk monopole antenna.The structure of the elliptical disk can make the antenna elements match well in a wide band.The bandwidth of the antenna is 3.1GHz to 10.6 GHz.The coupling current on the floor can be filtered out by the floor slot and the ground branch.The isolation between the two antenna elements is improved effectively,and the isolation between the two ports is greater than 15 dB in the whole UWB band.Secondly,a miniaturized MIMO antenna based on odd-even mode analysis decoupling network is designed.The unipole antenna unit is bent to prolong the current flow path on the patch antenna,thus increasing the electric length of the antenna and realizing the miniaturization of the antenna.Compared with the unbent antenna,the whole size of the bent antenna is reduced by 25.4%.Then the decoupling network is designed by using the odd-even mode analysis method,and the good matching anddecoupling of the two antenna elements are realized.The simulation and test results show that the two antenna elements are well matched and decoupled.The isolation between the two ports of the MIMO antenna with decoupling network is improved by more than 30 dB.Thirdly,the effect of mutual coupling between antennas on the channel capacity of MIMO system is studied.Based on the design of a miniaturized UWB MIMO antenna in Chapter 2,the calculation of the correlation coefficient matrix in arbitrary pattern is given,and the expression of the channel capacity of the MIMO system considering the mutual coupling effect and antenna correlation is derived.The effect of mutual coupling effect on channel capacity of MIMO system is simulated when the transmitter is equipped with omnidirectional antennas without considering the mutual coupling and correlation,and the receiver is designed for the miniaturized ultra-wideband MIMO antenna in Chapter 2.