Pseudo-differential operators for embedding formulae

A new method is proposed for deriving embedding formulae in 2-D diffraction problems. In contrast to the approach developed in [7], which is based on a differential operator, here a pseudo-differential, i.e., a non-local operator is applied to the wave field. Using this non-local operator a new embedding formula is derived for scattering by a single wedge. The formula has uniform structure for all opening angles, including angles irrational with respect to π; the earlier theory, [7], was valid only for rational angles.