Fast monostatic RCS computation in FEM based solvers using QR decomposition

A technique to reduce computational time in problems involving monostatic RCS computation using the finite element method is presented. In scattering problems, the excitation vectors for different angle of incidence are highly linearly dependent. Using this fact, the excitation matrix assembled over all incident angles can be approximated with a specified tolerance by QR decomposition with column rank that is much less than the number of incident angles of interest. The number of matrix solutions required is reduced to the effective column rank, resulting in significant reduction in computational time. Numerical examples highlighting the effectiveness of the proposed acceleration technique is presented.