The effect of wall thickness on the scattering of electromagnetic waves by open-ended rectangular cavities

Abstract

The scattering of electromagnetic waves by an infinitely long rectangular cavity with finite wall thickness is rigorously analyzed for E-polarization by developing a modified Wiener–Hopf formulation that extends the classical procedure to non-canonical geometries. The finite wall thickness introduces additional waveguide sections and coupling interfaces, which break the half-plane geometry underlying the standard Wiener–Hopf procedure. To overcome this challenge, the problem is reformulated as a system of modified Wiener–Hopf equations of the third kind (MWHE-3) by integrating the mode-matching technique within the cavity and wall regions. The resulting formulation accommodates the multiple reflections and modal interactions introduced by thick walls while preserving the mathematical rigor and edge condition satisfaction characteristic of the Wiener–Hopf approach. The solution involves coupled infinite systems of linear algebraic equations, efficiently solved through truncation. The scattered field is then evaluated using the inverse Fourier transform and saddle-point techniques. Numerical examples demonstrate the influence of wall thickness on the diffraction characteristics.