TIME-DOMAIN VECTOR-POTENTIAL ANALYSIS OF COMPLEX RF MULTILAYER STRUCTURES VIA SEGMENTATION TECHNIQUE Natalia Georgieva, Zhizhang Chen, Department of Electrical and Computer Engineering Dalhousie University P. O. Box 1000, Halifax, Nova Scotia, CANADA B3J 2X4 Wolfgang Oberhammer Wireless Networks Nortel/Northern Telecom P. O. Box 3511 Station C Ottawa, Ontario, CANADA K1Y 4H7 ABSTRACT The newly developed time-domain vector - potential (TDVP) approach, based on the finite- difference solution of the wave equation for the mag- netic vector potential , is applied to the analy- sis of multilayer structures typical for RF/microwave printed-circuit boards (PCB), widely used in the per- sonal communication systems (PCS) technology. The transient analysis of complex multiport discontinu- ities, where cross-talk and resonant phenomena oc- cur, is used to obtain their scattering parameters. The subsequent modeling of the whole unit is carried out by making use of the S-parameter library, prepared by the TDVP algorithm, and, a suitable microwave- circuit simulator, e.g. EESof Touchstone & Libra. The TDVP algorithm is also used to predict the res- onant frequencies of patch cavities which are encoun- tered in multilevel multiconductor structures. I. Introduction The study of the electromagnetic wave propaga- tion in complex multilayer structures is of substan- tial practical interest nowadays, closely related to the development of the third generation of wireless sys- tems, namely, the personal communication systems (PCS). PCS involve modules operating at about GHz frequency range. Therefore, their design often requires a full-wave analysis in order to avoid un- wanted cross-talk and resonance. The time-domain analysis is especially promising tool in these studies, featuring numerical efficiency, versatility and broad- band frequency results. The time-domain vector-potential (TDVP) ap- proach was recently proposed for transient electro- magnetic field analysis in [2]-[3] as an alternative to the most popular nowadays Yee-cell finite-difference time-domain (FDTD) technique [1]. The TDVP al- gorithm is based on the finite-difference treatment of the second-order scalar wave equation for each of the components of the magnetic vector potential . It re- duces the CPU time requirements with approximately 50%. It also offers an important advantage to reduce the memory requirements with at least one-third for structures free of dielectric-to-dielectric interfaces. In this paper the TDVP algorithm has been used to compute the S-parameters of complex-geometry discontinuities encountered in multilayer printed RF circuit boards in order to investigate unwanted cou- pling and cross-talk phenomena in a relatively broad frequency band. Further on, the S-parameters of these discontinuities have been used to model the behav- ior of a whole module via the commercial microwave simulator EESof Libra & Touchstone. The whole pro- cedure is time-saving and can be used for a reliable prediction of the behavior of complex RF/microwave circuit units. Two examples are presented in this paper: 1. Investigation of the dispersion characteristics of the coupling effects in two-level cross lines (Fig. 1). 2. Modeling of a split-ground RF circuit where un- 0-7803-4471-5/98/$10.00 (c) 1998 IEEE