Electromagnetic modeling of waveguides involving finite-size dielectric regions

A moment method for handling arbitrarily shaped 2-D and 3-D waveguides that involve either conductors, finite-size dielectric regions, or both is presented. A procedure for modeling the dielectric allows 2-D rooftop functions to represent both the 3-D polarization current in the dielectric and the surface current on the conductors, and precludes the presence of fictitious charge within the dielectric. Examples include coaxial, microstrip, and dielectric waveguides. Numerical convergence, consistency with physical principles, and agreement with the literature are demonstrated.