Plane Wave Diffraction by a Finite Parallel‐Plate Waveguide Cavity With Perfect Electric Conductor Loading: The Case of H Polarization

This work presents a rigorous analysis of H‐polarised wave diffraction by a finite parallel‐plate waveguide cavity with perfect electric conductor loading, employing the Wiener‐Hopf technique. The unknown scattered field is transformed using the Fourier transform, and boundary conditions are enforced in the transformed domain, leading to a system of simultaneous Wiener‐Hopf equations. These equations are solved through the application of factorization and decomposition procedures. The solution is exact but formal, as it involves branch‐cut integrals with unknown integrands and an infinite number of unknowns. Approximation procedures based on rigorous asymptotic analysis are proposed and employed, resulting in an approximate solution to the Wiener‐Hopf equations. The scattered field both inside and outside the cavity is determined by applying the inverse Fourier transform in conjunction with the saddle‐point method. Numerical results for the radar cross section under varying physical conditions are provided to illustrate the scattering behaviour in the H‐polarised case.