Design Of Functional Microwave Devices Based On Metasurfaces

Metamaterial is a kind of periodic structural unit material through artificial design,which can realize extraordinary physical properties that ordinary materials in nature do not have.One of the main features of metamaterials is that electromagnetic waves can be regulated by artificially designed specific structures.implement a specific function.As the two-dimensional equivalent of metamaterials,metasurfaces have the characteristics of small size and easy design compared with metamaterials,which have attracted the attention and favor of many researchers.By studying the relationship between matter and electromagnetic waves at the subwavelength scale,metasurfaces break through the inherent natural properties of matter,give matter other electromagnetic properties beyond the natural properties,and provide new ways of thinking and methods for the design of electromagnetic wave devices.The Huygens surface is an artificial electromagnetic surface that is analyzed and designed based on the Huygens principle.Transmission amplitude and transmission phase are a form of metasurface with the characteristics of low loss,low cost,and easy processing.By arranging the units in an appropriate phase distribution,the propagation direction of electromagnetic waves can be effectively changed.The main research contents of this subject are as follows:Firstly,the equivalent circuit of Huygens surface is analyzed.Taking the electric resonance structure and the magnetic resonance structure as the research core,the Huygens transmission unit structure is designed,and the I-shaped structure and the electric resonance structure are combined with the split ring respectively to obtain At15 GHz,the phase covers 360° and the amplitude remains above 0.84 in an 8-unit structure.Then use these 8 unit structures to build a beam deflection lens,which is excited by plane waves and feed horns respectively.After simulation and measurement,when the distance between the two adjacent units of the 8 unit structures is 7mm,the electromagnetic wave passes through the array structure.,the beam is deflected,and the deflection angle of the beam is about 20°,which is basically consistent with the20.92° calculated by the generalized Snell’s law.Through the asymmetric I-shaped structure,a 6-band absorber in the frequency range of 15 GHz to 30 GHz is realized.Due to the asymmetry of the structure,it is sensitive to both the polarization angle and the incident angleFinally,the multi-layer planar structure is used to design functions including deflecting lens,focusing lens and vortex wave generation.The unit structure is composed of three layers of dielectric and four layers of metal,and a metal ring is etched from each layer of metal to form annular gap.By optimizing the inner diameter of the circular patch,8 unit structures with a difference of 45° between two adjacent units at an operating frequency of 10 GHz and an amplitude of more than 0.78 are obtained.functions including deflection lens,focusing lens,and vortex wave generation can be realized by distributing the unit structure according to a certain phase.