Research On Integrated Design Of Radiation And Scattering Characteristics Of Metasurface Antennas

With the continuous development of information science and technology,the design of modern antenna systems tends to be multi-functional,integrated and intelligent.The attention and exploration of the integrated design of the radiation and scattering characteristics of the antenna are increasing day by day.This dissertation takes the metasurface antenna as the design carrier and conducts in-depth research on the method and key technology of the integrated design of its radiation and scattering characteristics.The main research contents can be divided into three parts as radiation improvement design and scattering control design based on metasurface-loaded antenna,integrated design of radiation and in-band scattering characteristics based on metasurface-loaded antenna,and integrated design of radiation and in-band co-polarized scattering characteristics based on metantenna.The first part investigates the radiation improvement design and scattering control design of the metasurface-loaded antenna.Under simulations and experiments,the proposed transmissive metasurface-loaded antenna and the reconfigurable reflective metasurface-loaded antenna achieve phased scanning range extension and polarizationinsensitive broadband near-field scattering focusing,respectively.(1)Transmissive metasurface-loaded antenna.First,an efficient transmissive metasurface unit cell with wide-angle incidence stability is investigated.Secondly,based on the Generalized Snell's Law,a multi-layer transmissive metasurface with symmetric bidirectional gradient is proposed to expand the phased scanning range.Then,the bidirectional gradient transmission metasurface is loaded on a compact array composed of conventional microstrip antennas for simulation and experiment.Finally,the numerical simulation and prototype measurement show that the transmissive metasurface-loaded antenna can effectively extend the scanning range of phased beams.(2)Reconfigurable reflection metasurface-loaded antenna.First,a varactor-loaded reflective metasurface unit cell is investigated for reflection phase tuning up to 360° in a wideband range by adjusting the bias voltage.Next,the cavity-backed antenna is coplanarly embedded in the reconfigurable reflection metasurface,and the reflection phase distribution is designed based on the principle of phase compensation.The simulation and experimental results show that the cavity-backed antenna loaded with the reconfigurable reflective metasurface achieves polarization-insensitive near-field scattering focusing in a broadband,indicating the ability of the reconfigurable metasurface-loaded antenna to control the scattering field.In the second part,based on the principle of phase compensation,a metasurfaceloaded antenna is proposed to realize the integrated design of high gain radiation and low in-band scattering.First,the anisotropic metasurface unit cells for transmission and reflection under y-and x-polarized plane waves are investigated.By changing the different structural parameters of each unit cell,the parabolic y-polarized transmission phase and the gradient-type x-polarized reflection phase are respectively realized.Secondly,a microstrip patch antenna loaded with anisotropic metasurface is designed.Simulation and experimental results show that the anisotropic metasurface loaded antenna achieves an integrated design of high gain radiation and low in-band scattering.In the third part,based on the characteristic mode analysis of the antenna,a metantenna for the integrated design of radiation and in-band co-polarized low scattering characteristics is proposed.(1)Anisotropic complementary metantenna.Firstly,based on the characteristic mode analysis,the modal behaviors of the uniform metantenna and the coding metantenna are compared.Secondly,two types of anisotropic complementary metasurface unit cells are proposed to reconstruct the coding metantenna,which combines the low sidelobe broadside pattern and the random reflection phase distribution to achieve low scattering.Finally,under the excitation of the butterfly-shaped double-slot substrate integrated waveguide,the simulation and prototype experiments show that the anisotropic complementary meta-antenna realizes the integrated design of low side-lobe radiation and in-band co-polarized low scattering.(2)Multi-resonant meta-antenna.First,based on the characteristic mode analysis,the resonance behaviors of the slotted metantenna and the conventional metantenna in radiation and scattering functions are compared.Second,a dual-polarized multi-resonant metantenna is proposed,which can achieve x-polarized low scattering and scattered beam deflection within the radiation band.Simulation and prototype experiments demonstrate that the multi-resonant metantenna achieves dual-polarized radiation,in-band x-polarized low scattering,and inband x-polarized scattered beam deflection.Moreover,the dual-polarized radiation properties of the multi-resonant metantenna are kept stable under different scattering functions.(3)Slot-connected metantenna array.First,a slot-connected metantenna formed by stacking a metasurface subarray and a substrate-integrated slot waveguide is studied and designed.The antenna has efficient reflection phase tuning capability and can keep the radiation characteristics stable against the changes of the metasurface subarray.Furthermore,a slot-connected metantenna array is constructed,and two complex and multi-characteristic scattered field shaping are realized using the phase compensation principle and the array product theorem jointly.Simulation and prototype experiments show that the integrated design of the slot-connected metantenna array realizes phased beam scanning and two in-band co-polarized scattered field shaping.