Rapid Design And Application Of Low Scattering Metasurface

Metamaterials are artificial periodic structures composed by subwavelength electromagnetic resonators.A series of new electromagnetic functions can be obtained with the metasurface,which has become generally acknowledged by researchers.One important application of the metamaterials is to achieve electromagnetic invisibility or transparency,which can greatly reduce the radar cross section(RCS).This paper focuses on the innovative design of the traditional artificial electromagnetic materials,and offers a rapid and efficient tool to manipulate the scattering behaviors of the metasurface.At the same time,the concept of transmission metasurface is put forward,which makes traditional metasurface more functional.Finally,the Iterative Fourier Transform(IFT)method is applied to all stealth designs.The main contents of this paper are as follows:(1)A new Iterative Fourier Transform algorithm is proposed to design the lowscattering metasurface.This method provides a route of backward scattering reduction by means of the inverse Discrete Fourier Transform(DFT)relationship between the scattering pattern and the element excitations.The Iterative Fourier Transform(IFT)method is introduced for the synthesis of the meta-array patterns by only controlling the reflection phase of each element.While encoding the metasurface with phase sequences to mimic the rough surfaces,diffusion-like reflections can be achieved over a wide frequency band.The method proposed in this paper can design the lowscattering metasurface precisely and efficiently.(2)A transmission metasurface is proposed and experimentally verified to realize a low scattering metasurface in X band,accompanied by a large transmissivity at low frequency as well.Different from previous studies,this design replaces the ground of the metasurface with a frequency selective surface(FSS)with prominent frequency dependent properties.Three basic elements are used to construct the whole metasurface,and the diffusion effect can be attributed to the destructive interference from different combination of elements with varied geometries.(3)A N-type structure with Pancharatnam-Berry phase is proposed in the low scattering metasurface design by the Iterative Fourier Transform method.It has a strong response to circular polarization wave,whose reflection phase of the cross-polarized component varies with the rotation angle.The final metasurface is simulated and experimentally verified under the illumination of circularly polarized(CP)wave.The combination of the iterative fourier transform algorithm and the P-B phase structure makes the lowscattering metasurface design more rapidly and efficiently.