Study of the slot mode in a structure including a delay line and a resonating piezoelectric plate

The results of the experimental and theoretical study of a structure including a delay line based on a lithium niobate plate of Y-X cut with two interdigitated transducers for exciting and receiving an acoustic wave with the shear-horizontal polarization in the frequency range 1.5-2.2 MHz are presented. The plate thickness was 0.35 mm. A resonating lithium niobate plate was located above the delay line between the transducers with a certain gap. Resonating plates of Z-X, Y-X–140° and Y-X+155° crystallographic cuts were studied. When RF voltage was applied to the input transducer, pronounced resonant absorption peaks were observed on the frequency dependence of the insertion loss. It has been established that with increasing width of the gap between the plates, the depth of the resonance peaks monotonically decreases and the peaks smoothly disappears. Moreover, for most peaks, the quality factor decreases with increasing gap width. The theoretical analysis of such structures showed good agreement between the theoretical and the experimental results. The developed structure shows promise for its use for multiparameter analysis of various liquids