Abstract

The diffraction of a plane electromagnetic wave by two rectangular grooves corrugated in a perfectly conducting plane is rigorously formulated in terms of a Fourier integral for two orthogonal polarizations. The problem can be treated as a combination of two separate ones, each involved with a single rectangular groove. The resultant matrix leading to the solution consists of submatrices appearing in the single groove scattering problem and others accounting for mutual coupling between grooves. The angular spectrum of the diffracted field is expressed in a series of Bessel functions, which is found to be computationally stable for solutions from the low to the high frequency regions. The diffracted-field patterns in the radiation zone are predicted by evaluating a Fresnel-type integral where contour integration and Watson transform are utilized to convert the original eigenvalue series into a radially fast convergent asymptotic series. Simulation results are generated for arbitrary scattering geometries. The far-field diffraction patterns are found to be a strong function of the ratio of the groove widths, heights, and the separation between them. The solution techniques can be easily generalized to solve the N-groove scattering problem.

© 1991 Optical Society of America