SURFACE ACOUSTIC WAVE RESONATOR

PURPOSE: To obtain a small sized surface acoustic wave resonator with a high Q by devising that Q deterioration due to the loss of a mode conversion into a radiation bulk wave is not caused even when a reflectance per reflecting element of a grating reflector is increased. CONSTITUTION: Plural grating reflectors 3 are arranged on a piezoelectric substrate 1 and an interdigital transducer 2 is arranged between the grating reflectors 3. In such a surface acoustic wave resonator, the conversion amount from a surface acoustic wave into a bulk wave of an electrode finger 4 of the interdigital transducer adjacent to a reflecting element 5 of the grating reflector 5 is made substantially equal to the conversion amount of the reflector from the surface acoustic wave into the bulk wave and an interval (d) between the reflector and the electrode finger adjacent to each other is set to be an interval by which bulk waves are interfered each other and cancelled.