A composite piezoelectric resonator with a lateral electric field

A new method of suppressing parasitic oscillations in a piezoelectric resonator with excitation of the transverse electric field is proposed. The method is based on spatial separation of the high-frequency electric field of a source and the resonating piezoelectric plate by means of an air gap. In this case, the tangential components of field in the piezoelectric plate are practically not attenuated, while the normal components are significantly reduced. The method is implemented by means of a composite resonator consisting of a glass plate with rectangular electrodes, an air gap, and a plate of lithium niobate 1of 128 Y–X cut. It is shown that there is an optimal width of the air gap that provides a good quality of series and parallel resonance in a frequency range of 3–4 MHz with a maximum quality factor of $\sim$ 15000 in both cases.