Accuracy improvement using a modified Gauss-quadrature for integral methods in electromagnetics

A Gaussian quadrature technique for evaluating shape-function-boundary-element kernel produce integrals over three-dimensional isoparametric boundary elements is presented. The procedure allows the integration of singular kernels of O(1/r) on curved surfaces. The integration of the normal derivative of Green's function is also possible. Integrals which exist in the sense of Cauchy principal values are dealt with using the addition-subtraction technique. The accuracy of the numerical integration scheme is compared with that of the double exponential formula and the subdivision technique. Some examples show the effectiveness of the procedure.>