A special higher-order finite element method for scattering by large cavities

Numerical computation of the radar cross section (RCS) of a large, deep open cavity is considered a very challenging problem in computational electromagnetics. A very efficient numerical technique was developed for the analysis of electromagnetic scattering from a large, deep, and arbitrarily-shaped open cavity. This technique is based on the finite element method (FEM) that is known for its capability to handle arbitrary geometries and complex material composition. The FEM mesh at the cavity aperture is terminated in an exact manner by the boundary-integral (BI) method. We enhance the efficiency of the technique using special mixed-order prism elements that have a higher-order interpolation in the transverse plane and a lower-order interpolation in the longitudinal direction. The numerical results demonstrate that this type of elements is optimal for the proposed technique.