| In recent years,with the advancement and development of science and technology,people’s lives are gradually moving towards the era of digitalization and information technology.Under the influence of environmental and cost constraints in wired communication,wireless communication systems,which can transmit information anywhere and anytime,have received widespread attention and research.As a frontend device for receiving and sending information,antennas play an important role in wireless communication systems.In the face of today’s complex electromagnetic environment and limited space utilization,antennas with miniaturized structure,high gain,large bandwidth and high isolation will definitely become the trend of future antenna design.As a kind of artificial composite material,electromagnetic metamaterials can obtain special electromagnetic properties that are not possessed by ordinary materials in nature by optimizing the size and structure design of their periodic units.This study applies the special physical properties of electromagnetic metamaterials to the design of microstrip antennas and MIMO(Multiple-inputmultiple-output)antennas,which can break through the size limitation of microstrip antennas and improve the optimization of microstrip antenna gain,bandwidth and other characteristics,and also can effectively reduce the coupling effect and improve the working bandwidth for MIMO antennas.Therefore,it has high research potential and value.In this paper,two kinds of electromagnetic metamaterial antennas are proposed and studied,and the main work is as follows.1.A non-connected "tian" low-frequency electromagnetic metamaterial array structure is designed and loaded on a fractal microstrip patch antenna operating at both1.8 GHz and 2.4 GHz to improve the antenna performance in terms of gain and bandwidth.The experimental results show that the antenna gain is improved to 4.49 d Bi in the 1.8 GHz operating band and 8.27 d Bi in the 2.4 GHz operating band,and the gain is improved by nearly 115% and 136%,respectively,compared to the unloaded electromagnetic metamaterial.In addition,the operating bandwidth of the antenna increases by 2.1% and 6.9% at 1.8 GHz and 2.4 GHz,respectively,and covers both low-frequency wireless communication bands(2.4 GHz-2.484 GHz),providing a solution for the design of wireless energy harvesting front ends in this frequency band.2.A new electromagnetic metamaterial structure based on a "ao" type is designed and etched on top of a dual-port MIMO patch antenna operating at 5.8 GHz,which improves the isolation and bandwidth of the MIMO antenna.Then a detailed comparative analysis of the electric field distribution of the coupled and decoupled arrays reveals the decoupling effect of the supersurface and analyzes the key factors of decoupling.The experimental results show that the antenna decreases the coupling degree by 10.87 d B and increases the bandwidth by 500 MHz in the operating band,which provides a solution for antenna decoupling in the high frequency wireless communication band and also has great potential in the face of future large-scale MIMO antenna system applications. |
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