Pulsed EM-field scattering by apertures

Abstract

Electromagnetic (EM)-field penetration through a slot in a planar sheet is a fundamental problem of EM theory that has been the subject of in-depth research in the real-frequency domain (FD) (see [1, 2] and the references therein). In this chapter, it is demonstrated how the problem of EM scattering by apertures in a perfectly electrically conducting (PEC) planar sheet can be solved in the time domain (TD). To that end, we shall first employ the Cagniard-DeHoop method of moments (CdH-MoM) to tackle the two-dimensional (2-D) problem consisting of a slot in a PEC screen. Second, under the assumption that the slot is relatively narrow, we shall pursue the approach previously applied to narrow strips (see Chapter 7) and describe its EM scattering properties in terms of Kirchoff-circuit equivalent parameters such as the "aperture admittance" [3]. With an emphasis on the proper problem formulation, the analysis is further generalized to incorporate the presence of a dielectric half-space, a rectangular filled groove and a homogeneous slot's filling. Finally, it is shown that the CdH-MoM computational methodology can be readily extended to analyzing the pulsed EM scattering by a bounded aperture of arbitrary shape.Throughout the chapter, the EM reciprocity theorem of the time-convolution type is taken as the point of departure (see [4, Section 28.4] and [5, Section 1.4.1]). For details regarding the EM scattering by slots in the real-FD, the reader is referred to thorough texts on the subject (see [6, Section 5.2] and [7, Section 14.9]).