MASS-LOADING EFFECTS ON CRYSTAL RESONATORS EXCITED BY THICKNESS ELECTRIC FIELDS

摘要

The report treats a single-mode resonator plate with equal mass coatings on its surfaces and excited by an electric field in the thickness direction. The usual restriction to low piezoelectric coupling coefficient is not made. From simple considerations regarding the equivalent network, the exact equations for the critical frequencies of interest are shown to follow directly. These are used throughout without approximation and solved numerically. Use of the exact relations allows high coupling materials to be covered as easily as low. Families of curves showing the variations of the resonance and antiresonance frequencies over a wide range of values of mass-loading, coupling coefficient and harmonic number are given. A new plateback parameter, valid for all piezoelectric substances, is also introduced. (Author)