Design And Application Of K-band Broadband Reconfigurable Metasurface

The development of mobile communication has promoted the renewal of communication physical layer hardware.In the application scenarios of future communication networks,electromagnetic wave control facilities need to overcome interruptions,enhance signals,reduce electromagnetic pollution,and reduce power consumption.Electromagnetic metasurfaces can regulate the phase,amplitude,and polarization of electromagnetic waves,and have the advantages of easy fabrication,low cost,and low loss.It provides a new way of thinking for electromagnetic wave regulation.Based on the reconfigurable metasurface,thesis focuses on the application research of dynamic scanning beam,vortex wave carrying orbital angular momentum,electromagnetic wave energy focusing and polarization conversion.Three different reconfigurable metasurfaces were designed by means of digital coding,laying the foundation for the digitization of metasurfaces.The main work of thesis is as follows:Using the idea of equivalent electromagnetic dipole,a 1-bit programmable metasurface unit operating in the K-band is designed.The equivalent electromagnetic dipole design makes the metasurface have similar resonance points in the two states,with a phase response of 180±20 ° in the 22-26.5 GHz range,and about 20% relative bandwidth in the K-band.The 1-bit metasurface unit is used to build a reflective metasurface array antenna,and the programmable metasurface system realizes a scanning beam of ±40 ° within the bandwidth range,completing the functions of OAM vortex electromagnetic wave and multi beam.Experiments have shown that the beam scanning ability of the metasurface reflection array antenna system is basically consistent with the simulation results,and it has a certain ability to regulate electromagnetic waves with a relative bandwidth of 17%.Through an asymmetric metal patch structure,a PIN diode is loaded in the direction of the y-polarization direction of the incident electromagnetic wave,and the design of a2-bit programmed metasurface unit in the K-band is completed.The metasurface has four states with a phase difference of 90 ± 20° in the frequency range of 24.4-25.4 GHz,extending the available bandwidth of the 2-bit metasurface.A 12×12 2-bit programmable metasurface system is designed to complete beam scanning with an elevation angle of±50°,and the gain is greater than 20 d Bi and the angle influence is small.The research results verify that the designed 2-bit programmable metasurface system has stronger scanning beam and electromagnetic wave focusing capabilities.In order to solve the functional unity of polarization converter,a reconfigurable polarization conversion unit that can switch polarization conversion mode in real time is designed.The research of reconfigurable multi-band multi-function polarization conversion unit is completed.By changing the switching state of the PIN diode,the linecircular polarization conversion is realized in the open state.line cross-polarization transition is realized in the off state.The unit has good polarization conversion characteristics within the oblique incidence range of 20° of the incidence angle,and has great application potential in the electromagnetic wave polarization conversion neighborhood in the future.