Curved Metamaterial Absorbing Structures Fabricated By Conformal EHD Printing

Electromagnetic metamaterials(EMM)are a kind of new artificial composite electromagnetic materials whose permittivity and permeability can be controlled.They can be applied to the absorption of electromagnetic waves and achieve the stealth of targets.Compared with traditional absorbing materials,metamaterial absorbing structures have advantages such as strong absorption,thin thickness and adjustable electromagnetic parameters,which can achieve perfect absorption of electromagnetic waves in specific frequency bands.The existing metamaterial absorbing structures are limited to the plane,which are difficult to meet the requirements of various complex surfaces in practical application.In this thesis,a curved metamaterial absorbing structure is designed on the basis of electromagnetic metamaterial absorbing technology.The curved absorbing structure is fabricated by conformal electrohydrodynamic(EHD)printing,and its performance is characterized.The main research work includes:(1)A curved metamaterial absorbing structure is designed,and its shape and dimensions are determined.The parameters of metal resonator and dielectric layer are studied by numerical simulation based on the analysis of the absorbing theory of metamaterial.The effects of different structural parameters on the absorption characteristics of the metamaterial absorbing structure are revealed,which provides guidance for the parameter design of the curved metamaterial absorbing structure.(2)The manufacturing process of curved metamaterial absorbing structure is studied.EHD lithography process on curved surface is proposed.The problem of printing on the insulating substrate is avoided by the integrated manufacturing method of adding and subtracting materials,which is printing first and then etching.The metamaterial absorbing structure can be manufactured on any curved surface by this process.According to the characteristics of the metamaterial absorbing structure and the existing problems,the manufacturing process is optimized.The slip law of the droplet on curved surface is investigated experimentally,and the droplet slip compensation algorithm is proposed to improve the slip phenomenon of the droplet on curved surface.The planarization algorithm of large area array on curved surface is proposed,which reduces the time needed to generate printing path on curved surface to1.79% and improves the overall process efficiency.The error of each axis of the fiveaxis linkage platform is measured and compensated to improve the printing precision.(3)The curved metamaterial absorbing structure is fabricated and its properties are characterized.The key performance indexes such as absorption frequency and absorption rate of the curved metamaterial absorbing structure are tested.The results show that the ideal absorption performance is obtained in the target frequency band,which verifies the correctness of the design principle and the effectiveness of the absorption.The test results of curved metamaterial absorbing structure and planar metamaterial absorbing structure are compared,and the performance differences and reasons are analyzed.