Research On Beam Deflection And Polarization Conversion Based On Metasurface

The continuous iterative development of wireless communication technology,the antenna is an indispensable and vital component,directly related to the success,stability,and efficiency of information transmission and reception.The polarization type and beam direction of electromagnetic beam have gradually become the focus of industry research.The traditional thinking is based on the principle of the antenna itself,which often has limitations.Regardless of the modulation in the orthogonal mode or the setting of the phase adjustment network,the workload and complexity of the circularly polarized antenna and the beam deflection antenna are continuously aggravated.The emergence of electromagnetic metasurfaces gives a new idea of antenna design,that is to seek the possibility of optimization from the level outside the antenna.The inherent advantages of low profile,simple structure,easy processing and easy assembly promote the metasurfaces to become the focus of the industry from the beginning,which can easily realize linear to circular polarization conversion,cross polarization conversion,beam deflection,beam convergence and other functions.In this paper,we mainly study the effect of polarization conversion and beam deflection based on metasurfaces,and carry out the simulation test combined with single line polarization antenna and metasurfaces.The main tasks are as follows:1?Research and design of single-line polarized dipole antenna.A square patch dipole is used in the unit structure,and a metal floor is placed at a quarter wavelength below it.Coaxial line is used for feeding and balun balance is carried out by metal conductor with the same outer diameter.Under the floor with a side length of 50 mm,the VSWR of3.34?5.28 GHz is about 2 or less,and the gain at 4.5GHz is about 7.07 d B.According to the requirements of co-simulation,simulation analysis with the floor side lengths of 75 mm and120mm was carried out.Finally,the antenna with a floor side length of 75 mm was processed and tested.And the results are basically consistent with the simulation.2?Research and design of polarization conversion metasurface and ant-surface joint simulation.Firstly,the unit structures of Chinese shape,wafer single slot and final type are designed successively.By using the coupling structure of single slit,hole digging in the middle layer,metal strip and symmetrical metallized via,the axial ratio of the final unit is about 3d B or less at 2.92?6.19 GHz,and the relative bandwidth is about 72%;the total transmittance of the final unit is about-3d B or more at 2.90?6.04 GHz,and the relative bandwidth is about 70%.The elements are arrayed according to 8×8 and co simulated with the linearly polarized antenna.About 59% of the bandwidth of the original antenna is achieved linear circular polarization conversion.In addition,the final structure unit can achieve about 84% of the relative bandwidth of 3d B axial ratio after parameter adjustment.Finally,the metasurface and antenna are processed and tested.And the results are basically consistent with the simulation.3?Research and design of beam deflection metasurface and ant-surface joint simulation.Firstly,direct type,double slit type and final 2-3-4 type cell structures are designed successively.By using the structure of double slit,double-layer circular hole coupling,three-layer main radiator coupling and symmetrical short-circuit metallized via,the 2-3-4self rotation 90° can produce 180° phase mutation effect.The phase difference of3.85?5.20 GHz is stable at about 163?217°,and the phase difference of about 81% of the frequency band floats at 163?195°.The transmission amplitudes in the range of3.82?5.43 GHz are both about 0.70 and above,and the amplitudes in 83% of the frequency bands are about 0.88 and above.In order to explore the best metasurface arrangement,the influence analysis of the x and y periodic arrangement and the 8421 arrangement analysis were carried out successively.Finally,the 284-0010 layout method is selected,and the ant-surface co simulation results show the VSWR band of less than 2 is expanded from3.27?5.28 GHz to 3.00?5.27 GHz.The beam deflection from-41° to-45° is basically realized.In the frequency band of 4.02?4.66 GHz and 4.93?5.10 GHz,the gain of-45° is greater than that of a single antenna at 0°.