Modified FDM with cartesian expansions for electromagnetic scattering from PEC targets

In this article, a modified scheme of the fast dipole method (FDM) is proposed based on the Cartesian tensor. To achieve separation between the field and the source, the Taylor series used in the FDM is an incomplete second-order expansion, which limits computational accuracy and flexibility. To address this issue, a Cartesian tensor is employed to expand the interactions between the far-group pairs. This approach allows for a complete expansion of any order and offers flexibility in precision control, enabling a balance between computational efficiency and accuracy requirements across different application scenarios. Moreover, the computational accuracy of the proposed method can be improved without a substantial increase in time and memory requirements compared to the FDM. The validity and accuracy of the proposed method are demonstrated with numerical examples.