Including high-frequency surface diffraction in a hybrid FEBI-MLFMM-UTD method

In this paper we propose a technique for including UTD surface diffracted fields which are diffracted from curved convex objects into a multilevel fast multipole implementation (MLFMM) of the Finite Element Boundary Integral method. We use Non-Uniform Rational B-splines (NURBS) representation for efficiently describing arbitrarily shaped objects. The dyadic Green´s function associated with UTD field scattered by these convex curved object is determined using a high frequency ray-based method and then inserted at the various levels of the MLFMM. Results show that the proposed hybrid MLFMM-FEBI-UTD technique for convex object allows a significant reduction in memory storage and computational effort, preserving however the accuracy in the field estimates^.