Leaky wave propagation in layered structures

The propagation characteristics of leaky waves in layered structures are analyzed as functions of overlay thickness. The behavior of different types of degenerate leaky waves with negligible attenuation, existing in quartz and lithium tetraborate, are studied when a thin film of ZnO or Al is deposited on the substrate. In particular, the propagation characteristics of a leaky wave are analyzed when its velocity approaches that of the limiting bulk wave. The general features in the behavior of leaky waves in layered structures are established as well as some peculiarities caused by the occurrence of a concavity on the slowness surface of a substrate material.