Symbolic Generation of Models for Microwave Software Tools

In this paper, we present a use of computer algebra systems (CAS) to derive the scattering parameter description of equivalent networks which are models of linear microwave devices, such as planar transmission line discontinuities. In this case, the use of an automated symbolic technique is a natural choice because manual derivation of scattering parameters is practically impossible, error-prone, and a fatiguing labour. Benefits of the presented symbolic approach are highlighted from the viewpoint of a microwave software tool. We exemplify our original symbolic algorithm by analyzing a four-port network that represents a microstrip cross-junction.