Wave Control And Functional Device Design Based On Metasurface

As a revolutionary two-dimensional artificial electromagnetic material,metasurface can flexibly regulate the amplitude,polarization and phase of electromagnetic wave in the subwavelength scale.Compared with the traditional three-dimensional metamaterial components,the components designed by using metamaterial not only overcome the shortcomings of large loss,difficult integration and manufacturing,but also achieve relatively excellent wavefront control ability,such as regulating the direction of electromagnetic wave propagation,polarization state,orbital angular momentum,circular dichroism and so on.Functional devices designed by metasurface have important application value in communication,imaging,sensing and other fields.Based on the excellent regulation ability of metasurface on electromagnetic wave,this thesis carries out the research work of functional devices based on electromagnetic beam regulation.The specific research contents are as follows:(1)Designed a high-performance reflector array antenna based on 5G communication working in a high frequency band lower than 6GHz.The antenna array uses the microstrip antenna based on U-shaped symmetrical structure as the feed antenna,which realizes the antenna gain of 6.3 d B.The phase mutation of the reflection unit in the range of 360° is realized by the size control.Based on particle swarm optimization,the reflector unit size array of far-field radiation is optimized,and the design goal of low sidelobe and high gain is achieved.The designed transmission array antenna finally realizes sidelobe optimization lower than-30 d B at5.8GHz and high gain antenna level of 23.0 d B.This array antenna has certain application value in the domestic high-speed 5G toll collection system,and can also be applied in the design of 5G directional antenna array.(2)A transmission array antenna based on millimeter wave band is designed.A combined metasurface transmission unit structure with strong transmission capacity is proposed,which can realize 360° transmission phase abrupt range.It has good polarization effect and oblique incidence effect in 28 GHz millimeter waves.Phase compensation is used to realize the design of small size transmissioning common metasurface structure,whose conformal cylindrical radius is 120 mm.Using the filter antenna with small size and high frequency selectivity as the feed antenna,the gain radiation of 8.2 d B spherical wave-like antenna is realized at 28 GHz.Finally,the gain level of the antenna array as a whole is 24.5 d B,the gain effect of the metasurface transmission array structure is 16.3 d B,and the SLL level is less than-17 d B.By adjusting the position of the feed antenna,the beam control range of ±12° is obtained.The high performance of the transmitted array makes it an ideal choice for the construction of scanning beam antenna and large-scale MIMO antenna array.(3)A wire-circular polarization converter working in mid-infrared terahertz frequency band is proposed.Based on the theory of dipole resonance,the polarization converter realizes the regulation of linearly polarized wave to circularly polarized wave in the dual-frequency range by means of resonant form.Based on the quality evaluation of circular-polarized electromagnetic wave by Stoker theory,the axial ratio of the circular-polarized wave converted by this converter is less than 3d B in the frequency range of 14.0 THz-20.1 THz and 23.5 THz-37.4 THz.At the same time,high quality circular polarization wave can be prepared in the range of ±40° oblique incidence Angle and ±20° polarization Angle.Therefore,the polarization converter has great application value in terahertz communication,sensing and integration.The thesis contains 58 figures,3 tables,and 93 references.