A novel hybrid technique is presented for the evaluation of electromagnetic scattering by electrically large bodies with cracks and cavities on their surfaces.This technique employs the edge-based finite-element method (FEM) to compute the scattering from the cracks and cavities

and PO and PTD to compute the scattering from the large bodies with the cracks and cavities filled with perfect conductors.A coupling scheme is then developed to combine these two methods.A set of numerical results is presented

demonstrating the accuracy

efficiency

and capability of the technique.As practical uses of the hybrid technique

a number of original results are then presented.It is shown that the hybrid technique has some advantages over other methods in regard to saving computer memory units and CPU time.