A Subgridding Conformal FDTD Algorithm for Analyzing Shielding Effectiveness of Metallic Casings

• Main Authors: Ching-Wen Chen, 陳靖文
• Other Authors: Chih-Wen Kuo
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/6ahy78

碩士 === 國立中山大學 === 電機工程學系研究所 === 107 === Modern electrical and electronic systems extremely rely on the use of electronic signals. When they are exposed to electromagnetic radiation, their interior electronic device might be susceptible to disturbance, causing signal distortion even damage the device. Usually a metallic enclosure is used to keep the electrical device from electromagnetic interference of outer environment. However, the ventilation holes or any other apertures of the enclosure will become paths that allow electromagnetic waves to propagate inside it. Therefore, the analysis of shielding effectiveness of metallic enclosures is an important electromagnetic interference issue. In this thesis, we present using the finite-difference time-domain (FDTD) subgridding algorithm to calculate the shielding effectiveness of a metallic computer case with circular ventilation holes. A conformal technique is used inside the subgridding region to improve the staircasing error resulting from the modeling of circular apertures. In the proposed framework, separate temporal and spatial interfaces are adopted. An adaptively adjusted time-stepping procedure is implemented to avoid late-time instability caused by subgrid cells and irregular grid cells. Comparisons of accuracy and efficiency of the proposed method with global fine grid FDTD and different subgridding meshing ratios are performed. The results show that using subgridding CFDTD (Conformal Finite-Difference Time-Domain) can obtain the same accuracy as fine grid FDTD and higher subgrid ratio with better efficiency.