Title :
Analysis of SAW grating waveguides considering velocity dispersion caused by reflectivity
Author :
Hirota, Kaoru ; Nakamura, Kentaro
Author_Institution :
Toyo Commun. Equipment Co. Ltd., Kanagawa, Japan
Abstract :
Conventional SAW grating waveguide analyses based on the scalar potential theory regard the phase velocity in the grating region as a constant. The velocity at the center frequency of the stop band was often used as a constant in those analyses. In reality, velocity dispersion is caused by the reflectivity of finger electrodes, and the velocity changes near the stop band. In this paper, a new approximate analytical model of SAW grating waveguides is proposed. This model includes the effect of the velocity dispersion, by placing a longitudinal component of wave number in such a way that it becomes a solution of the coupling-of-modes equations. To verify the adequacy of the model, 2-port resonators on 36.5°Y-X quartz and 45°X-Z Li2B4O7 are measured and compared with the computational results.
Keywords :
coupled mode analysis; equivalent circuits; interdigital transducers; lithium compounds; surface acoustic wave resonators; surface acoustic wave transducers; surface acoustic wave waveguides; ultrasonic dispersion; ultrasonic velocity; Li2B4O7; SAW grating waveguides; SiO2; Y-X quartz; apodized IDT; approximate analytical model; coupling-of-modes equations; equivalent circuit; finger electrodes; longitudinal component; near stop band velocity changes; periodic perturbation effects; reflectivity; substrate anisotropy; transverse mode; two-port resonators; velocity dispersion; wave number; Analytical models; Dispersion; Electrodes; Equations; Fingers; Frequency; Gratings; Reflectivity; Surface acoustic waves; Waveguide theory;
Conference_Titel :
Ultrasonics Symposium, 1999. Proceedings. 1999 IEEE
Conference_Location :
Caesars Tahoe, NV
Print_ISBN :
0-7803-5722-1
DOI :
10.1109/ULTSYM.1999.849390