Radar Cross Section Prediction Using Boundary Integral Equation Methods with Isoparametric Quadratic Surface Modeling and Iterative Solvers

ABSTRACT A boundary integral equation formulation for frequency domain near scattered field and radar cross section scattering is presented. It employs smooth, curved isoparametric quadratic elements for the modelling of both the geometry and field, along with high order gaussian quadrature for the integrations required to evaluate the matrix coefficients. The resulting matrix equations are solved using the complex biconjugate gradient approach. It is shown that this representation is efficient, allowing solutions to sizeable problems to be obtained, with accurate solutions with nodal separations as high as 1/5 of a wavelength. It is demonstrated that realistic geometries can require accurate integration, such as is provided by high order gaussian quadrature, for converged solutions to be obtained. Example results presented, all obtained on modest workstations, include a resonant cavity, the ∼ six wavelength NASA almond, and a dipole 20 wavelengths long.