Diffraction by, or diffusion into, a penetrable wedge

Approximate expressions are obtained for the field produced when an electro magnetic plane wave is diffracted by an arbitrary angled dielectric wedge, whose refractive index is near unity. The solution is obtained from an appl ication of the Kontorovich-Lebedev transform and a formal Neumann-type expa nsion. The diffraction problem is solved by firstly solving a related wedge diffusion problem and then using analytic continuation to obtain the solut ion for the diffraction problem. The results have applications in diffusion and wave propagation into a wedge.