Elastic surface wave devices

Abstract

The elastic surface wave device comprises a piezoelectric substrate having a dielectric constant of .epsilon..sub.2, a dielectric film having a dielectric constant of .epsilon..sub.1 and a thickness of h, and deposited on the piezoelectric substrate, and an inter-digital type input-ouput transducer formed on the dielectric film. The ratio of the dielectric constants .epsilon..sub.1 /.epsilon..sub.2, and a function 2.pi./.lambda..multidot.h proportioned to the thickness of the dielectric film are selected to satisfy a condition established in a frustum shaped region bounded by coordinate points P (.epsilon..sub.1 /.epsilon..sub.2 = 1/5,(2.pi./.lambda.).multidot.h = 0.1), Q(.epsilon..sub.1 /.epsilon..sub.2 = 1/5,(2.pi./.lambda.).multidot.h = 0.00016), R(.epsilon..sub.1 /.epsilon..sub.2 = 1/500,(2.pi./.lambda.).multidot.h = 0.0004), and S(.epsilon..sub.1 /.epsilon..sub.2 = 1/500, (2.pi./.lambda.).multidot.h = 0.006) on a graph wherein the ratio .epsilon..sub.1 /.epsilon..sub.2 is represented on the ordinate and the function (2.pi./80 ).multidot.h on the abscissa, where .lambda. represents the wavelength of the elastic surface wave. As a result, the energy of the elastic surface waves is propagated from the input transducer to the output transducer with a sufficiently large power.

Dependencies are inferred from the claim text.