Design And Acoustic Scattering Modulation Of Digitally Coded Acoustic Metasurface

Digital coding metasurface is a new branch in the field of materials research field,it will be digital coding thought into the design of the electromagnetic/acoustic artificial structure,it’s structure has different response characteristics of "digital" subwavelength unit,the unit in the arrangement of the space as a coding sequence,while the physical structure of the electromagnetic/acoustic wave control abstract for digital coding sequence of the regulation of the wave.The idea of controlling the wave field in physical space based on digital space design greatly improves the freedom of controlling the electromagnetic wave/acoustic wave,and is easy to realize the programmable adaptive control,which provides a new idea for the intelligent development of electromagnetic and underwater acoustic countermeasures technology in the field of information countermeasures.This paper by acoustic against technology development trend of intelligent as the research background,with acoustic scattering beam control and diffuse scattering signal suppression for the target of design,on the surface of the underwater acoustic digital coding ultra sound field control rule and mechanism were studied,and on the basis of exploring the broadband acoustic super active adjustable programmable digital coding on the surface of the design problem,The main research contents are as follows:1.The underwater acoustic digital coding unit structure based on pentamode metamaterial is designed.The analytical analysis model and finite element numerical simulation model of pentamode metamaterials based on thin straight beams were established.Combined with Gibson formula and elastic wave band structure analysis,the influencing factors and laws of equivalent parameters were systematically analyzed.The phase delay difference was designed to be greater than 180 ° within a certain frequency range.Underwater acoustic digital coding unit that can realize "0" and "1" digital coding.2.The scattering beam control and diffuse reflection suppression characteristics of pentamode-based coding metasurface for underwater acoustic are studied.The scattering beam control law and mechanism of a variety of ordered digital coding metasurface are systematically analyzed,and the design of the random coding metasurface with low scattering are studied.The simulation results show that the scattering wave attenuation of 10 d B can be achieved.3.An adjustable digital coding acoustic metasurface structural unit is designed.By controlling the rotation Angle φ of its central component,the response of the unit structure can not only switch between "0" and "1" at a specific frequency,but also ensure the accurate "0" and "1" response at different frequencies.It provides a feasible idea for programmable metasurface design with wide band and switchable digital coding.The research work in this paper provides technical support for the feasibility study of the application of digital coding acoustic metasurface for underwater acoustic countermeasures.