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Abstract

In a surface acoustic wave device for processing signals of relatively high frequencies, as of above 1 GHz, by the use of surface acoustic waves which propagate on the surface of a piezoelectric substrate, radiating bulk waves in the direction of depth of the piezoelectric substrate, an IDT structure is provided, which does not increase propagation loss and has sufficiently low electric resistance. The device comprises a piezoelectric substrate 10, and an electrode of a conducting film 12 for exciting, receiving, reflecting and/or propagating surface acoustic waves, and the surface acoustic waves propagate on the surface of the piezoelectric substrate, radiating at least one transverse component of bulk waves in the direction of depth of the piezoelectric substrate 10. An insulating film 18 has different thicknesses between first regions in the electrode, where the conducting film 12 is present, and second regions in the electrode, where the conducting film 12 is absent so that acoustic impedances of the first and the second regions with respect to the surface acoustic waves are substantially equal to each other.

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First Claim