Characterization of electromagnetic systems using Pade´ approximation with expansion at infinity

The Pade´ via Lanczos (PVL) method, with expansion at infinity, has been used to enhance the performance of the simulation program reduced-order modeling of electromagnetic systems (ROMES), developed based on the frequency domain finite difference (FDFD) method and the PVL algorithm with a finite frequency value used as the expansion point. The advantage of this new 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.