Cylindrical and Nonconformal Material Interfaces in the Finite Integration Technique

The present work addresses a fundamental issue of electromagnetic simulations by means of the Finite Integration Technique (FIT). This method is typically applied to Cartesian and, therefore, geometrically inflexible computational meshes. In order to achieve a high level of accuracy in a reasonable amount of time, the FIT commonly requires the simulated object's material interfaces to conform in a certain way to the mesh facets. Since this narrows its scope of application, we discuss two systematically different possibilities to transfer the expected accuracy from the conformal Cartesian case to other areas. On one hand, we abandon the Cartesian mesh in favor of a cylindrical one, which naturally conforms to many circularly shaped objects. In this regard, our main objective is the investigation and compensation of time domain methods' limitations that arise specifically due to inherent properties of the cylindrical mesh system. On the other hand, we present a generalized theoretical framework to enable highly accurate material modeling even in the event of nonconformal interfaces. Different means of applying it to practical simulations are proposed. Each introduced method is validated by means of numerical examples. Furthermore, a set of practice-oriented applications allows for comparing them to commercial simulation software and stresses their effectiveness.