ITD FORMULATION FOR THE CURRENTS ON A PLANE ANGULAR SECTOR

Approximate high-frequency expressions for the currents induced on a p erfectly conducting plane angular sector are derived on the basis of t he incremental theory of diffraction (ITD), These currents are represe nted in terms of those predicted by physical optics (PO) plus fringe c ontributions excited by singly and doubly diffracted (DD) rays at the two edges of the angular sector. For each of these two contributions, additional currents associated to vertex diffracted rays are introduce d that provide continuity at the relevant shadow boundary lines, The t ransition region of DD rays is described by a transition function invo lving cylinder parabolic functions. The asymptotic solution presented here is constructed in such a way to satisfy far from the vertex the e xpected edge singularities, which tend to be the same as those predict ed by the exact solution of the half plane. Numerical results are comp ared with the exact solution of the same problem and with moments meth od results for scattering from polygonal plates.