Applications of the Dirichlet-to-Neumann Boundary Operator in Transmission Line Modeling

The DtN operator is a useful tool in the characterization of interconnect structures. In combination with the Method of Moments, it can be used for transmission line modeling or to directly determine the internal impedance of conductors. This paper presents a new calculation method for the Dirichlet-to-Neumann (DtN) boundary operator, in the important case of a rectangular block, based on the superposition of slab waveguide modes. Especially for its non-differential form, some numerical issues need to be addressed. It is further explained how the DtN operator can be determined for composite blocks. The theory is illustrated by some numerical examples.