A new accurate analysis of periodic IDTs built on unconventional orientation on quartz

The analysis of periodic IDTs built on arbitrarily crystal oriented piezoelectric substrates requires the computation of a few fundamental parameters: the acoustic wave phase velocity, the strip reflectivity, the electromechanical coupling coefficient, the phase difference between transduction and reflection centers and the static capacitance. In this paper, we will show that, using a rigorous combined FEM/BEM numerical model for an infinite periodic structure based on the harmonic admittance concept, together with the general P-matrix formalism, it is possible to compute with a very good accuracy all the basic parameters, especially the phase difference between transduction and reflection centers. Numerical results will be shown for periodic IDTs built on various unconventional orientation on quartz, and the existence of the known NSPUDT orientation will be confirmed.