Decoupling Design Of Dual Frequency MIMO Antenna

Multi-input multi-output(MIMO)antenna technology is one of the key technologies in the field of 5G wireless communication.The technology can achieve spatial diversity,spatial multiplexing and beam assignment,improve signal transmission rate,increase channel capacity and improve spectrum utilization.However,multiple antennas are placed in communication equipment of small size,because the surface waves and spatial radiation waves generated in close range will cause interference between the antennas,resulting in strong mutual coupling between antenna units.Therefore,improving the isolation between antenna units is the core problem of multiple antennas.This thesis will focus on reducing the mutual coupling between MIMO antennas,and the main work can be summarized as follows:Firstly,a dual-band MIMO antenna with two ports is designed,which covers the WLAN(2.4GHz-2.48 GHz,5.15GHz-5.35 GHz,5.725 GHz-5.825GHz)frequency band.The unit antenna adopts the form of printed monopole,the low-frequency resonant unit is the inverted F antenna,and the high-frequency resonance is generated by the short cut line branch,so as to realize the dual-frequency operation of the antenna.The isolation degree of the antenna was increased to more than 25 d B by adding type I and type T branches respectively to achieve good isolation.Secondly,a MIMO antenna is designed to increase the current path to decouple the MIMO antenna.Respectively in the antenna to the floor and feed microstrip line load corresponding to the resonance frequency of about0.5mm and lines of the wavelength,width is 0.3mm,with microstrip line feeding.By studying the influence of the length,position and number of neutral lines on the antenna performance,the decoupling performance of only one neutral line 1 loaded on the antenna floor is the best,and theisolation degree of dual frequency band is more than 30 d B,which can realize the omnidirectional radiation of the antenna.Again,we design a comprehensive decoupled MIMO antenna of four units,placed on a symmetric MIMO antenna of four units,through the floor grooving,increase T side,plus bending neutral line combination of decoupling,with double T side to improve the level of two antenna coupling,with floor grooving and neutral line to improve the vertical direction of two antenna coupling,the resonant frequency of 2.45 GHz and 5.2GHz,finally realizes the antenna unit 1 and unit 2 min 23 d B,antenna unit 1 and unit 3isolation min.22 d B,antenna unit 1 and unit 4 the isolation of the lowest is25 d B,Isolation between each other's two ports has been improved.