Analysis of shielding effectiveness of enclosure with an aperture using FDTD method

The finite difference time-domain (FDTD) method was used to study the nuclear electromagnetic pulse (NEMP) waves and the continuous sinusoidal wave of different frequency coupling into one metallic container through a small aperture in one face of the container. The incident electric fields of NEMP were expressed by double exponential functions with two different decay constants. Based on the algorithm of thin material sheets in the FDTD method, the finite-difference expressions of the electromagnetic components at the common boundary of two thin sheets are dealt with distinguishingly. A method to compute the shielding effectiveness of the metal enclosure with an aperture and thin walls is introduced. The time-domain behavior of the electric field inside the metallic container excited by the waves was obtained by the FDTD method. The results of FDTD and ETL method are compared in order to verify the validity of FDTD modeling.