Patent ID: 7482896

Claim:
A surface acoustic wave apparatus comprising at least one interdigital transducer, the interdigital transducer disposed such that a plurality of comb-shaped electrodes respectively connected to a pair of common electrodes are interleaved; and a pair of reflectors, respectively provided at the both sides of the interdigital transducer, wherein a region with the plurality of interleaved comb-shaped electrodes is formed with two regions which are a first overlapping region and a second overlapping region with overlapping-lengths weighted along a propagation direction of a surface acoustic wave, wherein the first overlapping region and the second overlapping region are in contact or overlapped in a direction vertical to the propagation direction of the surface acoustic wave, wherein in either the first or the second overlapping region, an overlapping-length weighting envelope curve is formed so as to have at least two or more changing points, in the propagation direction of the surface acoustic wave, at which points the overlapping-lengths weighting envelope curve changes from being increasing to decreasing or from being decreasing to increasing, and wherein patterns of the envelope curves of the first and second overlapping regions are identical.