Effect of stepped bi-mesa structures on spurious vibrations of AT-cut quartz plates

In this pager, the effect of stepped bi-mesa structures on the coupling of vibrations in AT-cut quartz plates is analyzed theoretically. Since strong coupling of thickness-flexure modes are of interest, straight-crested waves propagating along the X axis are treated. Calculated results for the stepped bi-mesa structure show that the coupling strength as estimated from its mode chart decreases to about one-third that of a bi-mesa resonator. The characteristics of bi-mesa structures appear to be amenable to further improvement by the use of a stepped bi-mesa structure.