SURFACE ACOUSTIC WAVE FILTER

PROBLEM TO BE SOLVED: To sufficiently reduce cost by automatically applying effective spurious measures. SOLUTION: Two IDT 2 and 3 (interdigital transducer) or more are arranged on the surface of a piezoelectric substrate 1 along the propagation direction of a surface wave. A rough surface obtained by applying unevenness processing to the surface of the piezoelectric substrate 1 is provided near both end parts when the piezoelectric substrate 1 is viewed in the propagation direction of the surface wave. The rough surface has width of λ or more in the propagation direction of the surface wave when the wavelength of the surface wave is defined as λ and has length extending to the entire surface of the piezoelectric substrate 1 viewed in the direction perpendicular to the propagation direction of the surface wave. COPYRIGHT: (C)2007,JPO&INPIT