Surface-wave-like mode in slot line

Propagation properties of the surface-wave-like mode in slot line are investigated with the spectral domain analysis. This surface-wave-like mode is an odd dominant mode with a magnetic wall symmetric plane placed at the center of the slot. Its field distribution is similar to that of the TM/sub 0/ mode supported by the surrounding structure. It exists in the lower frequency regime and evolves into a nonphysical and nonspectral real mode in the higher frequency regime. Unlike other surface-wave-like modes in planar transmission line, the surface-wave-like mode in slot line does not evolve into a leaky mode.