Patent ID: 8680743

Claim:
A surface acoustic wave device comprising: a quartz crystal substrate having Euler angles (−1.5°≦φ≦0.5°, 117°≦θ≦142°, 42.79°≦|ψ|≦49.57°); an IDT which has a plurality of electrode fingers on the principal surface of the quartz crystal substrate and excites a surface acoustic wave in a stopband upper end mode; and a pair of reflectors which respectively have a plurality of conductor strips and are arranged on both sides of the IDT with the IDT sandwiched therebetween along the propagation direction of the surface acoustic wave, wherein inter-electrode-finger grooves are recessed in the surface of the quartz crystal substrate between adjacent electrode fingers of the IDT, inter-conductor-strip grooves are recessed in the surface of the quartz crystal substrate between adjacent conductor strips of the reflectors, the wavelength λ of the surface acoustic wave and the depth G of the inter-electrode-finger grooves satisfy the relationship 0.01λ≦G, the line occupancy η of the IDT and the depth G of the inter-electrode-finger grooves satisfy the following relationships, and −2.0000 ×G/λ+ 0.7200≦η≦−2.5000 ×G/λ+ 0.7775 where 0.0100λ≦ G≦ 0.0500λ; −3.5898 ×G/λ+ 0.7995≦η≦−2.5000 ×G/λ+ 0.7775 where 0.0500λ ≦G≦ 0.06952; and an IDT line occupancy η and a reflector line occupancy ηr satisfy the relationship η<ηr.