Spectral method for multiple edge diffraction by a flat strip
A spectral iteration scheme is employed to analyze time-harmonic and transient scattering of an E-or H-polarized incident plane wave by a perfectly conducting plane strip. The scattered field is synthesized by successive interactions between the edges, with each interaction modeled by half-plane diffraction. The plane wave spectrum generating a particular order of diffraction consists, in addition to the incident plane wave excitation, of a portion determined from the previous diffraction. The multiple integral spectral representations constructed in this manner satisfy the edge condition, and they are in a form suitable for inversion into the time domain by the modified Cagniard-de Hoop method. Asymptotic reductions for special cases yield agreement with results from other methods, when available. Numerical calculations including up to triple diffraction have been performed for H- and E- polarized impulse and Gaussian pulse scattering. The results are clearly seen to repair the deficiencies of wavefront approximations at longer observation times, and from comparison with data generated independently by eigenfunction expansion, they describe accurately the total scattered response, owing to the high damping rate of higher-order diffractions.
multiple integral spectral representations
scientific article; zbMATH DE number 3970187