Design And Research Of Wideband MIMO Antenna Based On Meta-materials

With the advent of the 5G era,MIMO antenna will become the mainstream of future antenna development because of its high channel capacity,strong anti-jamming ability.However,in MIMO antennas,the miniaturization of antennas inevitably brings about a high degree of coupling between array elements,which affects the overall performance.Therefore,how to reduce the coupling between the array elements becomes an urgent problem to solve.In addition,circularly polarized antennas are widely used because they can not only receive signals with different polarization from any direction,but also transmit signals received by arbitrarily polarized antennas.Therefore,the circular polarization of the antenna is also a current research hotspot.In recent years,metamaterials have been widely used in the field of microwave antennas because of their special electromagnetic properties.Based on the above background information,this paper focuses on the application of metamaterials in wideband MIMO antennas by using metamaterials as a starting point.First,a wideband MIMO antenna array based on metamaterial is proposed.This metamaterial works in the X-band and is mainly used for decoupling MIMO antenna array.Through theoretical model simulation and theoretical derivation,the principle of metamaterial decoupling is explained.The final designed wideband MIMO antenna array based on metamaterial operates at 8.5-11.5 GHz（relative bandwidth is 30%）.With the assurance that the antenna array’s bandwidth has little effect,the modified antenna array has a lower coupling degree(S₁₂<-15 d B)and higher gain（>5 d Bi）.In addition,the optimized antenna array also exhibits excellent diversity performance.Therefore,the proposed MIMO antenna array has many advantages such as wide frequency band,low mutual coupling,and small size.Secondly,a wideband circularly polarized zhong-shaped MIMO antenna array based on metamaterials is proposed.The structure innovatively combines Chinese characters and the appearance of the antenna,and uses two kinds of metamaterials:one is a round wheel shaped metamaterial,which is mainly used for decoupling wideband MIMO antennas,and the other is a double V shaped and oblique cross shaped metamaterial,which is mainly used for linear to circular polarization of broadband MIMO antennas.After many optimizations and adjustments,the finally designed antenna array operates in 2.22-2.75 GHz（relative bandwidth is 24.7%）,which has high isolation with the coupling degree less than-18 d B and wide axial ratio bandwidth characteristics with the axis ratio within 3 d B in its bandwidth.In summary,two wideband MIMO antenna arrays based on metamaterials are designed in this paper,which have higher performance than traditional antennas and can adapt to more complex environments.