Abstract A body of piezoelectric material propagates acoustic surface waves. For launching or absorbing those waves, an electrode array is coupled to a surface portion of the body. The array includes a bifilar coil comprising a pair of windings coiled over the surface. A source or load is coupled between one end of one winding and the remote end of the other winding, with the remaining ends of both windings coupled together. The spacing between adjacent turns of the windings is effectively one-half the wavelength of the acoustic waves at the operating frequency. The bifilar winding is shown either in a form where it is coiled around a cylinder or where it is nested concentrically on a surface. In one species, an input transducer launches waves in two directions around a cylinder, and an output transducer absorbs waves coming from both of the two directions. The bifilar coil contributes an inductive reactance to compensate the clamped capacitance of the transducer.
A system as defined in claim 1 in which said interaction means includes: a second electrode array including another bifilar coil comprising interleaved third and fourth windings coiled over said surface with the spacing between adjacent turns of said other bifilar coil being effectively one-half the wavelength of the acoustic waves at said predetermined frequency; a load coupled between one end of said third winding and the remote end of said fourth winding; and means for connecting the remaining ends of said third and fourth windings to the remaining ends of said first and second windings.
Claim 2
Dependent Claim
29 words
A system as defined in claim 1 in which said body is of elongated cylindrical shape and said bifilar coil is coiled around the cylindrical surface of said body.
Claim 3
Dependent Claim
41 words
A system as defined in claim 1 in which said body includes a generally planar surface on which said transducer is disposed with said bifilar coil of generally flat configuration and having the winding turns thereof nested concentrically on said surface.
Claim 4
Dependent Claim
44 words
A system as defined in claim 1 in which said body is of cylindrical shape and said bifilar winding has its turns nested concentrically on an outer peripheral surface of said body to launch said acoustic waves along a curved path over said surface.
Claim 5
Dependent Claim
28 words
A system as defined in claim 1 in which said bifilar coil contributes inductive reactance substantially compensatory of the clamped capacitance created by said windings and said body.
Claim 6
Dependent Claim
134 words
An acoustoelectric signal translation system comprising: a generally cylindrical body of piezoelectric material propagative of acoustic waves; a surface wave transducer disposed on a first peripheral portion of said body and responsive to input signals for launching acoustic surface waves respectively along each one of a pair of circumferential paths individually extending in opposite directions from said transducer; and interaction means, comprising a second surface wave transducer coupled to a second peripheral portion of said body spaced from said first peripheral portion and disposed in both of said paths, responsive to said launched acoustic surface waves in both paths for utilizing the signal energy translated thereby, in which said body is a hollow cylinder and in which a conductive metallic core extends axially through said Body to serve as a shield between said transducers.