Analysis of frequency-temperature behavior of surface acoustic wave (SAW) under periodic IDT

In this paper, we incorporate two thermal models with periodic FEM/BEM to analyze the temperature-frequency behavior of SAW under periodic IDT. One is the classical model based on Campbell´s theory, which has been widely used. We find that this model fails to predict temperature-frequency behavior of SAW for some cases, although we can get accurate results for many cases of some cuts and modes by using this model. The other is based on piezoelectric, Lagrangian equations. This one his proved to be a general model for the analysis of thermal effects on SAW, and is more accurate than the first one. But the application of this model is limited to quartz-based devices, because the temperature coefficients of material constants for other materials for piezoelectric, Lagrangian equations are not available at present. In practice, the two models are useful for the designing of SAW devices.