Surface wave leakage phenomena in coupled slot lines

Surface wave leakage phenomena of coupled slot lines are investigated with spectral domain analysis. When the guided mode in the coupled slot lines changes from bound mode to leaky mode, there is a frequency range, called "spectral gap," where only nonspectral solutions exist. If the width of the center conductor or slots is increased beyond a certain value this spectral gap may disappear, resulting in a frequency range where both bound mode and leaky mode can exist simultaneously.<>