Robust application of the complex images technique to the full-wave analysis of slot-like transmission lines

摘要

In this Letter, the mixed potential integral equation (MPIE) method is used in conjunction with the complex images technique to carry Out a full-wave analysis of a multiconductor coplanar waveguide (CPW) embedded in a layered substrate. Special attention is paid to the correct application of the method so as to maintain high accuracy and stability of the numerical results. It is shown that the procedure only provides a robust and accurate approach when the complex images expansion variable is properly chosen and the singularities of the Green's functions are properly handled. Numerical problems arise in any other case. In particular, it is demonstrated that the two-level sampling scheme used by some authors is not enough to overcome the numerical problems. However, the two-level sampling method is shown to be essential to deal with the presence of extremely thin substrate layers such as those found in multichip-module-deposition (MCM-D) technologies.