SCATTERING OF ELECTROMAGNETIC WAVES BY A SINUSOIDALLY STRATIFIED HALF-SPACE: II. DIFFRACTION ASPECTS AT THE RAYLEIGH AND BRAGG WAVELENGTHS

Abstract

The diffracted field of a plane wave incident obliquely from air onto a sinusoidally modulated half-space is investigated by employing a rigorous formal solution, together with graphical constructions and equivalent circuits, which have already been derived by Tamir and Wang (1966, Part I). The field in the air region is shown to be influenced considerably by Wood's anomalies of the Rayleigh type. The location of these anomalies is determined by the onset of propagation or evanescence for modes in either the air or the dielectric regions; their orders of magnitude are estimated by means of a network which describes the air–dielectric interface. In the stratified dielectric, the field is strongly affected by an interference process that peaks at the Bragg wavelengths and produces a resonant behavior of the modal amplitudes. This results in a strong standing-wave field pattern in the form of repetitive oblong rectangular cells with interesting power-flow properties. Additional details of the fine field structure are treated extensively and numerical data, which are in excellent agreement with the considerations and results obtained by analytical and graphical means, are given.