Patent ID: 7750533

Claim:
A surface acoustic wave (SAW) device, comprising: a piezoelectric substrate; at least one interdigital transducer (IDT) formed on the piezoelectric substrate; and reflectors disposed at both sides of the IDT, wherein the piezoelectric substrate is made of a quartz crystal flat plate where a cut angle “θ” of a rotated Y-cut quartz substrate is set in −64.0°<θ<−49.3° with a crystalline Z axis and a propagation direction of the surface acoustic wave is set at 90°±5° with a crystalline X axis, an excited wave is SH wave, an electrode film thickness “H/λ” normalized by a wavelength of the IDT is 0.05≦H/λ≦0.07 where “λ” is a wavelength of the exciting SAW, and a ratio of an electrode pitch between the IDT and the reflector “Lt/Lr” is set in a range of 31.50×(H/λ) 2 −4.435×(H/λ)+1.133≦Lt/Lr≦−3.000×(H/λ) 2 +0.5000×(H/λ)+0.9796 where “Lt” is the electrode pitch of the IDT and “Lr” is the electrode pitch of the reflector.