Contents I. Introduction
IN RECENT years, it has become increasingly important to estimate the electromagnetic shielding effectiveness (SE) of the cases that enclose various types of electronic equipment. For optimal cost efficiency, using a numerical technique during the design phase of the equipment is indispensable for estimating the SE of various shapes and materials for these enclosures. The finite-difference time-domain (FDTD) method [1] is well known as being one of the most useful numerical techniques for such problems. However, for calculating the effectiveness of an enclosure whose thickness is much smaller than the operating wavelength, the conventional FDTD method has a disadvantage. For the FDTD modeling, very fine cells must be used in the region with thin sheets, and these fine cells reduce the time-step size because of the Courant–Friedrich–Levy (CFL) stability condition [2], which results in an increase in computational effort, such as the CPU time. In fact, several micrometer-thick thin shielding sheets, which are generally fabricated using conductive paints or electroless plating techniques on plastic surfaces, are often used today, thus, the inefficiency of the FDTD method is a very serious issue for optimizing the design process.
