Research On The Wideband And End-Fire Antennas Based On Metasurface

End-fire antennas have many advantages like high gain,high directivity,simple structure,simple feeding and so on,which are usually applied to the wireless communication fields such as satellite communication,mobile communication,and radar detection.Antenna acts as a core component of the wireless communication system,whose performances directly affect the communication quality of the wireless communication system.Due to many limitations of narrow bandwidth,and large size of traditional end-fire antennas,in this thesis,our research focuses on wideband and miniaturized end-fire antennas,which combines metasurface design concept with traditional antennas.In details,the index-modulated metasurface structure is applied to the design of the traditional end-fire antennas,which provides an innovative idea for traditional end-fire antennas' design.The main research contents of this thesis are listed in the following aspects:Firstly,the research background and significance of wideband end-fire metasurfacebased antennas are introduced,and the development history and research status of metasurface and end-fire antennas are respectively introduced.Based on the subwavelength periodic unit model,the unique electromagnetic characteristics of metasurface are explored,and the in-phase reflection and surface wave propagation characteristics are explained.Secondly,the metasurface characteristics of guiding and controlling the propagation of surface wave have been explored.A wideband bi-directional surface wave antenna based on one-dimensional modulated metasurface is proposed.The refractive indexmodulated metasurface structure is applied to design surface-wave antenna,which achieves good bi-directional pattern,low profile and wide-band performance,and the working mechanism of the proposed planar end-fire surface wave antenna is analyzed theoretically.Thirdly,taking advantage of the surface-wave propagation characteristics of metasurface and the basic theory of traditional antennas,the plan of integrated design is presented.A “capsule”-shaped dipole with two pairs of rectangular steps is as the launcher,and a metasurface is designed consisting of index-gradient patches and indexfixed patches.Based on the principle of phase compensation,a miniaturized wideband one-dimensional modulated metasurface antenna excited by the dipole is designed.The bandwidth and gain of the antenna have been greatly improved,and the design of low profile and miniaturization is realized.Finally,in order to enrich the application scenarios of metasurface in end-fire antenna,a wideband unidirectional metasurface antenna is proposed,which could concentrate radiation energy in a certain direction to obtain higher gain.The antenna consists of a microstrip line to slotline transition structure,a driver dipole and indexgradient patches.Simulation results shows that the proposed antenna the characteristics of unidirection,wide band,high directivity,and good unidirectional radiation pattern over the entire operation bandwidth.To summarize,three designs of wideband end-fire antennas based on metasurface fully demonstrate that combining design concept of metasurface and traditional end-fire antenna has great research value in realizing the antenna performance of wideband,miniaturization and high performance.