Even–Odd-Mode Quasi-Static Analysis of Symmetrically Coupled Microstrip Lines with Bi-Isotropic Media

This paper presents a quasi-static analysis of symmetrically coupled microstrip lines on a bi-isotropic Tellegen substrate using the hybrid boundary element method (HBEM). The electromagnetic behaviour of this structure is analyzed under even- and odd-mode excitations in order to determine characteristic parameters. Also, the influence of the degree of bi-isotropy on these parameters is quantified. The bi-isotropic medium, as well as both strips, is modelled by discretizing the interfaces and introducing equivalent electric and fictitious magnetic charges while satisfying the corresponding boundary conditions. Unlike conventional boundary element method formulations, the proposed approach directly forms the system matrix without extensive boundary integrations, leading to reduced computational complexity and computation time. The HBEM results are validated against finite element method solutions obtained using FlexPDE software, showing a close agreement. The presented results demonstrate that the proposed HBEM formulation provides an efficient and accurate approach for quasi-static parameter extraction in complex multiconductor transmission structures.