Analysis of microstrip structures with an inhomogeneous dielectric layer in an unbounded region

The method of lines (MoL) is used to compute the frequency dependent propagation characteristics of planar waveguides with an inhomogeneous dielectric layer. To simulate unbounded regions, absorbing boundary conditions (ABC) are used. It is shown that in this case excellent results are achieved even if the boundaries are placed very close to the dielectric edge of the structure.