High-Order VSIE-Based Reduced Basis Method for Fast Modeling of Anisotropic-Metallic Targets

In this letter, a high-order volume–surface integral equation (HOVSIE)-based reduced basis method (HOVSIE-RBM) is presented for the fast calculation of the wideband electromagnetic scattering of anisotropic-metallic objects. In the HOVSIE-RBM, two main processes, i.e., the offline process and the online process, are included. During the offline process, the sampling current vectors are first calculated by the HOVSIE, where a high-order hierarchical vector base (HOHVB) is applied to reduce unknowns in the anisotropic medium. Meanwhile, the hybrid multilevel accelerated Cartesian expansion multilevel fast multipole algorithm is used to accelerate the iteration of HOVSIE. During the online process, integrating with RBM can avoid the replicative near-region impedance matrix-vector multiplications (IMVMs). Moreover, the wideband scattering can be obtained mainly by calculating far-region IMVMs, rather than the classical iteration of HOVSIE. Therefore, deteriorated iteration caused by the increased basis order of HOHVB can also be avoided. Meanwhile, compared with the low-order volume–surface integral equation RBM, HOVSIE-RBM has higher interpolation efficiency and requires less memory cost, when solving the same wideband scattering problem. Interpolation accuracy, memory cost, and efficiency will be demonstrated by two numerical examples.