Research On Localized Wave Synthesis Based On Metasurface

Localized wave(LW)refers to a type of beam or pulse that can maintain a certain form of non-diffraction propagation in space,and is also called non-diffracting wave(refered to as NDW).A basic physical phenomenon of traditional electromagnetic wave propagation is diffraction.During the propagation process,electromagnetic waves diffuse in various directions in space,which results in a significant decrease in receiving efficiency and spatial resolution.Local waves have the characteristics of high directivity and no diffraction.It will have broad application scenarios in the fields of dense channel communication,high-resolution microwave imaging,and efficient wireless energy transmission in the future.As a new type of electromagnetic wave control method,artificial electromagnetic materials can flexibly adjust the amplitude,phase,and polarization of electromagnetic waves.In recent years,it has become a research hotspot.This article combines two research directions of artificial electromagnetic materials and local waves,uses the transmission-type metamaterial unit to regulate the beam,and synthesizes the local wave field by the new electromagnetic research method of time inversion electromagnetics This method can be used to synthesize multiple localized wave more conveniently.This article aims to form a new set of localized wave(LW)synthesis schemes in the electromagnetic field.The main research contents of this article include the following five parts:(1)Firstly,the research significance and background of LW are explained,and then the domestic and foreign research trends in the field of beam control of artificial electromagnetic materials are introduced.(2)Exploration of Localized Wave Synthesis Based on Time-Reversal(TR).First,the new electromagnetic wave research method of time inversion and the main characteristics of time inversion are briefly introduced.Then,the time inversion method proposed by us is used to simulate the Bessel wave synthesis.The feasibility of this method was confirmed,and the theoretical foundation was laid for the next design of the metasurface.(3)Three kinds of hypersurfaces that can generate Bessel waves are designed using time inversion method.Its functions are to generate vertical inversion Bessel wave beams,inclined Bessel waves in any direction,and multi-beam Bessel waves,and processed and tested an array size of 350 mm × 350 mm,which can generate a tilt angle of 30 °.The inversion of Bessel wave metasurfaces has shown that the design can accurately and efficiently output electromagnetic waves in the direction of the target,laying a foundation for future wireless energy transmission applications.(4)A non-diffraction vortex beam was studied.Firstly,the high-order Bessel wave was studied.The field distribution and propagation characteristics of the first-order Bessel wave were specifically analyzed,and its vortex and non-diffraction characteristics were verified.It was proved that it did carry orbital angular momentum.The two methods of designing and simulation verify two kinds of metasurfaces,which can generate inverse first-order Bessel waves and first-order Bessel waves tilted by 30 °,which widens the application scenarios of diffraction-free vortex beams.(5)Finally,the research carried out in this article is summarized,and the direction for the next research is determined.I hope that future research can be more convenient and efficient for local wave synthesis based on this article,and that the synthesis of local waves is not limited to Bessel wave.