Abstract: A surface wave acoustic delay line is formed of a set of electrode assemblies disposed on the surface of a block of crystalline material propagative of a surface acoustic wave. In each of the assemblies, the electrodes are arranged in an interdigitated pattern. Reflected waves are cancelled by the construction of an additional electrode in each of an electrode assembly, the additional electrode extending only one-half the distance of the other electrodes and being spaced from an adjacent electrode by one-quarter wavelength. This introduces a 180.degree. phase shift between portions of relected waves which then cancel to remove the reflection. Also, in the case of closely spaced electrode assemblies, additional electrodes, equal in shape and size to the electrodes of the assemblies, are introduced between the assemblies in the form of a grid which propagates surface waves without reflection.

Abstract: Disclosed is a multiterminal acoustic surface wave transducer which has a unidirectional response characteristic over a selected operating frequency band and is capable of launching and receiving surface waves in a body of piezoelectric material. In a specific embodiment the transducer includes a plurality of sets of first, second and third parallel electrodes arranged in cascade on a surface of the piezoelectric material with a center-to-center electrode spacing equal to one-third wavelength of a selected frequency within the frequency band. Corresponding electrodes in each set are interconnected, with each group of interconnected electrodes forming a terminal of what is in this case a three terminal transducer. When a three phase electrical signal is supplied to the terminals of the transducer with a 120.degree. phase separation between terminals, the transducer will launch a corresponding surface wave in the piezoelectric material in the direction of phase progression among the electrodes.