Optimal Design Of Broadband High-gain Metasurface Antennas

Microstrip antennas have been used in modern mobile communication,radar,missile,satellite,medical equipment and other wireless communication systems,Attributed to they have the advantages of light weight,small volume,thin profile,easy conformal,low cost,easy integration,etc.,so it since its introduction.However,the traditional microstrip antennas also have the disadvantages of narrow frequency band,large dielectric loss,small power and so on.With the development of modern wireless communication technology,the performance requirements of the antenna are becoming more and more high.The main development direction are broadband,high gain,low loss,miniaturization and intelligence of the antenna.If an antenna can not only meet the requirements of wideband and high gain,but also achieve miniaturization,it will make a significant contribution to the development of wireless communication technology.The emergence of metamaterials has brought new opportunities to the development of antennas.Metasurface is the two-dimensional plane instead of threedimensional structure metamaterials,not only maintain the special electromagnetic properties of metamaterials,but also have the advantage of occupying less physical space.Using metasurfaces to design microstrip antennas can not only broaden the antenna bandwidth,increase antenna gain,but also reduce the antenna profile size.Based on the systematic analysis of the metasurface,broadband,high-gain and lowprofile antennas was optimized and designed in this thesis.The specific research contents are as follows:1.A metasurface broadband antenna with a rectangular unit structure of equal size is designed.Firstly,a fan-shaped microstrip feed structure is adopted at the end of the antenna and multiple resonant points are optimized according to the transmission line model to further expand the bandwidth of the metasurface antenna.Secondly,in order to explore the mechanism of generating multiple resonant points,a non-uniform additional patch element structure was designed to expand the antenna impedance bandwidth.Finally,the overall size of the antenna is optimized by using genetic algorithm to obtain the widest impedance bandwidth.2.A metasurface broadband high-gain antenna with a hexagonal unit size gradient structure is designed.A new metasurface with a gradient structure of hexagonal element size is proposed to expand the bandwidth based on the mechanism that the non-uniform distributed patch element structure can expand the bandwidth.The non-uniform distributed array can also improve the gain of the antenna.The measured results show that the impedance bandwidth of the antenna reaches 54%(3.99?6.93GHz),the maximum gain reaches 12.05 d B,and the gain remains above 8d B in the range of4?6GHz.The antenna has wide beam characteristics in the whole frequency band,achieving the characteristics of wide band,high gain,low profile and so on.