Analysis of Time-Domain Shielding Effectiveness of Enclosures Above Lossy Half-Space Using an Improved Half-Space FDTD Method

Since shielding enclosures which are widely used in electronic systems and devices are usually located close to the ground, the effect of ground reflection must be taken into account when analyzing the electromagnetic (EM) characteristics of enclosures. Consequently, the assessment of time-domain shielding effectiveness (SE) is a composite problem of the lower half-space and the enclosure above it. However, the application of existing half-space algorithms is often limited by the high computational demand and the complex half-space Green's function, which is difficult to derive and calculate. This article proposes an improved half-space finite-difference time-domain method without employing the half-space Green's function, while effectively reducing the computational memory and time. Based on this new method, the time-domain SE of enclosures above lossy half-space is analyzed; additionally, the difference between the coupling field and time-domain SE, on the one hand, and the free space and half-space, on the other hand, is discussed in detail. The numerical results show that the time-domain SE is reduced significantly owing to the reflection effect of the lower half-space. To sum up, this method provides an effective time-domain approach for the analysis of EM characteristics of objects above the complex half-space.