Acoustic surface wave-apparatus having dielectric material separating transducer from acoustic medium

Claim 2

An acoustic surface wave transducing system, comprising: an acoustic surface wave propagation medium; an electromechanical transducer having a plurality of conductive fingers arranged on said medium; and a dielectric material separating all of the fingers which comprise said transducer from said medium; whereby the combination of said transducer and said dielectric material forms a transducing system for coupling energy to and from said propagation medium.

Claim 3

A system in accordance with claim 1 wherein said dielectric material comprises a layer of dielectric material arranged direCtly on said medium, said layer being relatively thin with respect to the wavelength of surface waves propagating in said medium.

Claim 4

A system in accordance with claim 2 wherein the thickness of said layer is less than one-half a wavelength and is uniform thereby providing a transducing system having a uniform coupling ability for each of said plurality of fingers.

Claim 5

A system in accordance with claim 3 wherein said dielectric has a low dielectric constant with respect to said medium, thereby providing a transducing system in which reradiation can be minimized.

Claim 6

A system in accordance with claim 3 wherein said dielectric material has a low piezoelectricity with respect to said medium, thereby providing a transducing system in which bulk wave scattering is minimized.

Claim 7

An acoustic surface wave transducing system, comprising: an acoustic surface wave progation medium; an electromechanical transducer having a plurality of conductive fingers arranged on said medium; and a dielectric material separating all of the fingers which comprise said transducer from said medium and having a relatively low dielectric constant and piezoelectricity with respect to said medium; whereby the combination of said transducer and said dielectric material forms a transducing system in which the low piezoelectricity of said dielectric matieral minimizes bulk wave scattering and in which the low dielectric constant of said material enables minimization of reradiation.

Claim 8

An acoustic surface wave transducing system, comprising: an acoustic surface wave progation medium; an electromechanical transducer having a plurality of conductive fingers arranged on said medium; and a dielectric material separating all of the fingers which comprise said transducer from said medium and having a relatively low dielectric constant and piezoelectricity with respect to said medium; whereby the combination of said transducer and said dielectric material forms a transducing system in which the low piezoelectricity of said dielectric matieral minimizes bulk wave scattering and in which the low dielectric constant of said material enables minimization of reradiation.

Claim 9

A system in accordance with claim 6 wherein said dielectric material comprises a layer of dielectric material arranged directly on said medium, said layer being relatively thin with respect to the wavelength of surface waves propagating in said medium.

Claim 10

A system in accordance with claim 7 wherein the thickness of said layer is less than one-half a wavelength and is uniform thereby providing a transducing system having a uniform coupling ability for each of said plurality of fingers.

Claim 11

A system in accordance with claim 8 wherein said medium is lithium niobate and wherein said dielectric layer is silicon monoxide and has a thickness approximately between one/thirtieth and one/fifteenth of the wavelength of surface waves propagating in said medium.

Claim 12

An acoustic surface wave tapped delay line, useful as a matched filter, comprising: an acoustic surface wave propagation medium which imparts a finite time delay to surface waves traveling between two points on said medium; a dielectric material arranged directly on a portion of said medium, said layer being relatively thin with respect to the wavelength of surface waves propagating in said medium and having a relatively low piezoelectricity and dielectric constant with respect to said medium; and first and second electromechanical transducers, arranged entirely on said medium, at least one of which has a plurality of finger pairs each corresponding to a tap on said medium; whereby, when surface waves are launched by one of said transducers, they encounter the finger pairs of the other transducer in time sequence due to the wave propagation velocity of said medium, creating a tapped delay line in which the low piezoelectricity of said dielectric material minimizes bulk wave scattering and in which the low dielectric constant of said dielectric material enables minimization of reradiation.

Claim 13

An acoustic surface wave tapped delay line, useful as a matched filter, comprising: an acoustic surface wave propagation medium which imparts a finite time delay to surface waves traveling between two points on said medium; a dielectric material arranged directly on a portion of said medium, said layer being relatively thin with respect to the wavelength of surface waves propagating in said medium and having a relatively low piezoelectricity and dielectric constant with respect to said medium; and first and second electromechanical transducers, arranged entirely on said medium, at least one of which has a plurality of finger pairs each corresponding to a tap on said medium; whereby, when surface waves are launched by one of said transducers, they encounter the finger pairs of the other transducer in time sequence due to the wave propagation velocity of said medium, creating a tapped delay line in which the low piezoelectricity of said dielectric material minimizes bulk wave scattering and in which the low dielectric constant of said dielectric material enables minimization of reradiation.