Application of the Pade approximation via Lanczos (PVL) algorithm to electromagnetic systems with expansion at infinity

ROMES (reduced-order modeling of electromagnetic systems) was developed based on the frequency domain finite difference (FDFD) method in our lab [1]. Previously, the Pade via Lanczos (PVL) algorithm was used for the reduced-order modeling of the linear system with finite frequency values used for the expansion point. In this paper, the PVL method, with expansion at infinity, has been used to enhance the performance of ROMES. The advantage of this method is avoidance of the LU decomposition step that is costly both in speed and memory. It also provides better wide frequency band results than PVL with expansion at a finite frequency, which only gives correct results near the expansion point. The disadvantage is that the dimension of the reduced-order model must be higher relative to PVL with finite value expansion for accurate approximation of the original electromagnetic system. Although it suffers from this disadvantage, PVL with expansion at infinity makes it possible to solve some complicated electromagnetic problems efficiently.