Theory for shear horizontal surface acoustic waves in finite synchronous resonators
An analytic approach is developed for simulating synchronous resonators employing shear horizontally polarized surface acoustic waves, such as surface transverse waves, and leaky surface acoustic waves on LiTaO/sub 3/ and LiNbO/sub 3/ substrates. The approach, based on a simplified parametrized Green's function theory, allows the description of the localization of the wave and the interaction with bulk acoustic waves. An analytic expression is found for the harmonic admittance of an infinite periodic electrode array, and approximate corrections for finite structures are presented. The model enables fast computation of the admittance of synchronous resonators, and it compares favorably with experiments and numerical simulations.
Propagation of Transverse Surface Acoustic Waves in Rotated Y-Cut Quartz Substrates Under Heavy Periodic Metal Electrodes
Abstmct-A theory of the propagation of transverse surface acoustic waves on a piezoelectric substrate with heavy periodic metal electrodes on the surface is presented. The mechanical properties of these electrodes are assumed to be nonnegligible. Dispersion relations for waves near the stopband of the periodic electrode array are analyzed. It is found that the mass of the electrodes exerts a considerable effect on the shape and mutual positions of the stopbands for short-circuited and electrically isolated electrodes. The discussion is based on an approximation for the effective surface impedance that relates the amplitudes of the electric and elastic fields observed at the surface of a piezoelectric substrate. The parameters of this approximation are given for rotated Y-cut quartz substrate. The theory presented can readily be generalized to the case of Rayleigh surface waves.
Prediction of net pressure on pressure equalized cavities
Abstract A numerical model has been developed for prediction of net pressure on pressure equalized cavities. The results based on this model show good agreement with those obtained from mock-up tests. Parametric studies verify that reductions in cladding load are possible, with proper design of curtain walls.