Simulation Design Of Multi-frequency MIMO Antenna Based On Artificial Electromagnetic Materials

With the continuous innovation of wireless communication technology,the modern and contemporary wireless communication field needs to face the test of higher capacity and higher efficiency of data transmission.Antenna is an indispensable unit in this field,which needs to meet the design requirements of multi-band,miniaturization,high isolation and so on.However,the old antenna design concept can not meet such requirements,so we need to seek new research objectives and content.Thanks to metamaterials,we have more possibilities to solve these challenges.The appearance of metamaterials enables them to possess some unique electromagnetic properties that cannot be matched in nature,such as perfect reflection phenomenon,inverse Doppler phenomenon,backward wave property,etc.,all of which are realized by carefully designed structures and sizes.Based on the in-depth study of antenna design theory and metamaterial theory,this paper proposes a novel metamaterial unit structure and applies it to monopole antenna and MIMO antenna to improve its performance and reliability.The detailed work arrangement of the paper can be summarized as follows:(1)A novel multiple input multiple output(MIMO)decoupling method based on artificial materials is proposed.In this method,dragonfly shaped magnetic negative metamaterial unit design is used,which is placed between two antennas to reduce the mutual coupling between the antennas.The experimental results show that,compared with the MIMO antenna without metamaterial,the coupling coefficient S21 of the antenna element is effectively reduced from-12.4d B to-33.1d B at the center frequency,and the coupling coefficient S21 is all below-20.7d B in the whole working band range.The results show that this decoupling method can significantly improve the performance of MIMO system and reduce the influence of mutual decoupling.Meanwhile,the loading of metamaterials has little effect on the working bandwidth and radiation characteristics of the original MIMO antenna.(2)A dual-frequency MIMO antenna is designed,which is equipped with metamaterial to make it mutually coupled and reduced in the corresponding frequency band.A metamaterial composed of upper,middle and lower layers of metal structure is designed.By analyzing the performance parameters of the dual-frequency metamaterial in its working frequency band,The simulation results show that the MIMO antenna equipped with metamaterial decreases from-30.9d B to-36.2d B at3.5GHz and from-15.7d B to-20.6d B at 5.7GHz,achieving a good isolation effect.The addition of metamaterials does not affect the working bandwidth of the MIMO antenna.