Analysis of open-ended radiating structures based on SFELP (segmentation approach/finite elements/Lanczos-Pade)

A hybrid procedure for analyzing passive microwave circuits based on the mode matching (MM), two and three dimensional finite-element methods (FEM) and the segmentation concept was introduced by Rubio, Arroyo and Zapata (see IEEE Trans. Microwave Theory Tech., vol.47, no.9, p.1746-49, 1999). Rubio, Arroyo and Zapata (see IEEE Trans. Microwave Theory Tech., vol. 49, no.3, p.509-516, March 2001) applied the symmetric Pade via Lanczos algorithm (SyMPVL) to the segmentation approach (SFELP method). With this procedure the behavior of each region is described from a generalized admittance matrix (GAM) that is quickly calculated in a wide band from a reduced-order model of the transfer function. In this paper SFELP is extended to the analysis of open-ended radiating structures such as the cavity-backed microstrip antenna depicted. A new module with a spherical port, where a spherical mode expansion is employed, and which keeps the form of the transfer function required to apply the SyMPVL algorithm, is introduced.