ACCURATE SOLUTIONS OF MAXWELLS EQUATIONS AROUND PEC CORNERS AND HIGHLY CURVED SURFACES USING NODAL FINITE-ELEMENTS

A method is presented for computing accurate solutions of Maxwell's eq uations in the presence of perfect electrical conductors (PEC's) with sharp corners and highly curved surfaces using conventional nodal fini te elements and a scalar/vector (S/V) potential formulation, This tech nique approximates the PEC with an impedance boundary condition (IBC) where the impedance is small, Critically, it couples both potentials t hrough this boundary condition, rather than setting the scaler potenti al to zero, This permits cancellation of the tangential components of the vector potential, resulting in an accurate normal electric field, The cause for the inaccuracies that nodal methods experience in the pr esence of sharp PEC corners or highly carved PEC surfaces is elucidate d, It is then shown how the inclusion of the scalar potential cures th ese deficiencies permitting accurate solutions, Spectral analysis of t he resulting finite element matrices are shown validating the boundary conditions used, Examples are presented comparing a benchmark solutio n, conventional PEC and IBC boundary conditions, and the new SN potent ial IBC on a PEC wedge and PEC ellipse, In both cases the new SN IBC p roduces superior results.