Improving the Accuracy of the VIE-SWG Scheme With the Use of a Strict Boundary Condition

For calculation of internal field distribution in and electromagnetic scattering from dielectric objects, it is shown that the conventional solution scheme for volume integral equation (VIE) using the Schaubert-Wilton-Glisson (SWG) basis functions by Method of Moments (MoM) suffers from the accuracy problem，especially for high permittivity cases. The analysis shows that this problem is resulted from the use of the half SWG basis functions directly for the boundary elements without any additional restrictions for normal continuity condition. Based on this analysis, a divergence free condition is applied in boundary elements for the electric flux density vector which results in a revised version of the VIE-SWG (VIE-SWG-R) scheme. Numerical results show that the revised version is accurate not only for low but also for high permittivity cases. More importantly, it is much more accurate than the conventional VIE-SWG scheme when the mesh size varies between λr/8 and λr/15 with λrbeing the wavelength in a dielectric body, particularly for high permittivity cases. Besides, the VIE-SWG-R scheme results in fewer numbers of unknowns than the conventional scheme for the same discretization. Additionally, this revised solution scheme can be implemented by a minor modification of the conventional VIE-SWG scheme.