A new theoretical approach for the coupling coefficient in the monolithic structures

Based on Tiersten's analysis an accurate calculation of the coupling coefficient dependence on geometrical dimensions and mass-loading for quartz and langasite monolithic structures was performed. We have studied the effect of mass-loading on the coupling coefficient of langasite and quartz monolithic filters and we have found that the effect on langasite filters is tower than on quartz filters. A better agreement between input data and experimental attenuation characteristics is obtained when the rigorous theoretical approach is used in the calculation of the coupling coefficient. The relation between the coupling coefficient and the material constants is discussed on crystals grown by various laboratories.