Modal transition phenomena in shielded microstrip with anisotropic substrates

Modal transitions involving the quasi-TEM (transverse electromagnetic) mode and higher-order modes in shielded microstrip and suspended microstrip with anisotropic substrates are studied. For the class of anisotropy studied, the largest eigenvalue may not correspond to the quasi-TEM mode at higher frequencies. It is shown that the dispersion curves of the quasi-TEM and higher-order modes do not intersect, but rather pass through a transition/coupling region and interchange mode types.<>