Multiple diffraction of electromagnetic waves by a wedge of concave shape

Multiple diffraction of short-wavelength electromagnetic waves by a wedge of concave shape is considered. Analysis is performed on the basis of geometrical theory of diffraction (GTD) and uniform theory of diffraction (UTD). The resulting wave field is represented as a superposition of a variety of edge-diffracted and specularly reflected waves, treated as “channels of multiple diffraction”. Algorithms of UTD allow of describing birth and disappearance of diffraction channels under evolution of the wedge shape. Classification of diffraction channels is suggested and dominant channels are selected. The “four/five channels model” of scattering is proposed, which describes effectively diffraction of electromagnetic waves by steep and breaking water waves of mesoscale spectrum and embraces the main interference and polarization phenomena, characteristic of low-grazing angles of radar sounding, including: (a) phenomenon of enhanced backscattering, (b) Brewster phenomenon, responsible for suppression of vertical polarization, and (c) phenomenon of “super events”: gigantic spikes of radar cross section. It is shown that radar cross section for plain individual mesowave of 30 cm height and of 1 m front width may reach as large values as 1-10 m2.