Application of the FDTD method in the modeling of bent coaxial structures

An extended finite difference time domain (FDTD) method is presented to model a typical interconnection structure consisting of a closed three-dimensional bent coaxial waveguide. In order to obtain a faster, more accurate, and more elegant implementation, some aspects of the FDTD method were studied. A transition formula to connect meshes with difference cell size is proposed. The derived formula was tested in a one-dimensional case, but is applicable in more-dimensional discretization schemes. A formula to correctly describe a transition between a discretization scheme in a Cartesian system and in a cylindrical coordinate system is obtained. This is a second-order discretization formula for the first-order derivatives in Maxwell's equations. The validity of this approach is illustrated by a three-dimensional example.<>