주기 슬릿 구조의 전자기파 해석 연구

Abstract

This dissertation describes several numerical analyses of electromagnetic scattering problems of periodic slit array. Method of Moments is used to obtain an equivalent circuit to analyze the characteristics of electromagnetic transmission and scattering. Based on a matrix formation of Method of Moments including an assumption that the width of each slit is very small, several important things can be extracted without calculating the complex periodic Green function and adapting Floquet theorem. Results are well agreed with results of the commercial simulation, but as the width of each slit increases, the difference increases. So, one might use a rigorous mode matching technique for the accurate solution. Therefore, using mode matching technique and the orthogonal functions, we can release from the limitation of very narrow slit array. Results from the mode matching technique are very accurate compared to results of the commercial simulator. Fourier transform was not used in the general mode matching technique. Transmission coefficient is represented into the -1st higher order mode of incident transverse magnetic (TM) wave, and is equivalent to the simulation result. Additionally, this chapter demonstrates the case of the periodic slit array filled with bilayers dielectric of double positive value. A dispersion relation of waveguide modes is studied in cases of transverse electric/magnetic (TE/TM) wave. If a frequency of 1st higher order waveguide mode is higher than that of -1st higher order Floquet mode, an effective dielectric constant of bilayers dielectric can be used as some constant. But if a frequency of 1st higher order waveguide mode is smaller than that of -1st higher order Floquet mode, an effective dielectric constant of bilayers dielectric becomes a specific function of frequencies. These two cases are considered in this paper. In the next, various researches for the projects of the laboratory about the rolled steel and scale layer are illuminated. Scale layer is formed by bonding the oxide in the air during the manufacturing processes. Scale layer is a component that must be eliminated and spoils the appearance of the steel product. But this scale layer cannot be eliminated unless an additional process, such as plating and pickling procedure, is performed. So, if the characteristics and thickness distribution of scale layer can be analyzed, the manufacturer can consider whether the additional processes are needed, or not. For this purpose, the various researches and experiments have been performed and demonstrated. In last chapter, the composed structure of patch and aperture elements for frequency selective surface is illuminated, and the simulation results are demonstrated mainly. In addition, measurement system using microwave in iron-foundry plant are introduced for future works or projects.