APPLICATION OF THE EIGENMODE TRANSFORMATION TECHNIQUE FOR THE ANALYSIS OF PLANAR TRANSMISSION-LINES

The eigenmode transformation technique is formulated for the analysis of inhomogeneously filled shielded waveguides containing metal inserts , The permittivity of the filling medium may be an arbitrary function of the transverse coordinates, The method is based on expanding the el ectromagnetic field in terms of the eigenmodes of the corresponding em pty shielding waveguide, The metal inserts have first the effect of li nearly transforming the eigenmodes of the empty guide into those of th e shielded waveguide containing the metal inserts (including the TEM-m odes), Next the inhomogeneity of the filling medium is taken into acco unt which leads to a proper matrix eigenvalue problem, In addition an alternative formulation is derived from a variational approach, Result s of both formulations are compared for a shielded circular dielectric waveguide, The eigenmode transformation technique is applied to vario us types of planar transmission lines, i.e., coupled microstrip lines, finlines, and coplanar lines, The results are compared with those of other methods.