Design,Manufacture And Analysis Of Microwave Absorber Comprising Metal/Dielectric Thin Films

Thin film technology is one of the main technologies in the field of electromagnetic wave absorber.In this thesis,microwave absorber based on metal/dielectric nano-films has been proposed and investigated with structure similar to that of the Salisbury screen except that the resistive sheet is replaced by FSS of square patch array of the nano-films.We have explored the absorbers from these aspects:equivalent circuit model,electromagnetic full-wave simulation and the actual sample measurement with arch method and free-space method.The resistive nano-films and patch arrays were directly manufactured by electronic-beam evaporation of Fe/SiO2 multilayer film with certain mask.By carefully tuning the patch size,the thickness of the dielectric spacer and the specification of the nano-films,we obtain the optimized performance of broadband microwave absorbing.These new absorbers with adjustable parameters,light weight,large surface area,soft texture and many other advantages,have a good application prospect in the electromagnetic shielding,electromagnetic compatibility,and radar stealth.The main works of this paper include the following aspects:1.We described the research background of film materials in the field of optics and electromagnetics,and introduced the electromagnetic characteristics,application and research progress of the nano metallic film in the electromagnetic wave absorption.2.We analyzed the working principle of the Salisbury screen by using the equivalent model,introduced the different loss types of the Salisbury screen,and studied the relationship between the absorbing properties and electromagnetic parameters by electromagnetic full-wave simulation.3.By introducing the types of frequency selective surfaces,we analyzed the working principle by equivalent circuit model,put forward the optimum design,and studied the relationship between the absorbing properties of resistive frequency selective surfaces and electromagnetic parameters by electromagnetic full-wave simulation.4.We introduced the preparation method of thin film materials and based on the optimum design,manufactured Salisbury screen absorber and resistive frequency selective surface absorber by the electron beam evaporation method with certain mask.5.We described the working principle of arch method reflection measurement system and the free-space method transmission measurement system,measured the absorbers based on the time domain technique,verified the consistency of the wave absorbing properties and the simulation results.