Improvement of frequency sweeping by MoM matrix interpolation combined with Stoer-Bulirsch algorithm for multilayered structures

In this paper, an efficient improvement of frequency sweeping for multilayered structures is proposed, which is based on the combination of MoM impedance matrix interpolation and the Stoer-Bulirsch algorithm. With fast and accurate evaluation of multilayered Green´s functions, the MoM impedance matrix can be efficiently computed, and therefore suitable for interpolation because of its smooth and polynomial-like variance toward frequency. By selecting Chebyshev nodes in the whole band as preliminary sampling points, all the impedance matrices at adaptive frequency sampling (AFS) points can be efficiently interpolated, from which one can acquire the current coefficients immediately. A patch antenna and a dual-layer coupled filter are modeled and calculated by the proposed method over a frequency band. Very good agreements have been found between the proposed method and EM simulations by ANSYS HFSS, while a significant improvement on efficiency is realized.