Showing papers on "Interdigital transducer published in 1969"

Analysis of Interdigital Surface Wave Transducers by Use of an Equivalent Circuit Model

Abstract: Immittance, transfer, and scattering characteristics are studied for acoustic surface wave transducers of the interdigital electrode form. Linear network models are used to represent the transducer as a chain of identical three-ports which are acoustically in cascade but electrically in parallel. Transducer operation at acoustic synchronism is described theoretically and compared to current experimental data for transducers operating at 100 MHz and fabricated on lithium niobate. Favorable lithium niobate configurations for efficient, broad-band transducer operation are given. Scattering characteristics as a function of electric load are discussed. Low values of acoustic reflection loss are predicted theoretically and observed experimentally when the electric load and transducer capacitance are in resonance. The frequency dependence of transducer radiation immittance is studied, and the response is found to be analogous to the response of an endfire antenna array.

Excitation of elastic surface waves by spatial harmonics of interdigital transducers

Abstract: The electric field distribution from a surface wave interdigital transducer is investigated. Expressions for the various spatial harmonics and the capacitance of a transducer applied on an anisotropic, small-coupling propagation medium are derived. Experiments are consistent with the calculations.

Excitation and Detection of Surface Elastic Waves in Piezoelectric Crystals

Abstract: The amplitude of the surface elastic wave produced by the application of an alternating voltage to an interdigital arrangement of electrodes on the surface of a piezoelectric medium is determined. The electric field produced by the surface electrodes is calculated subject to the assumption that the piezoelectric coupling of the material can be neglected. This electric field acts as the forcing term for the inhomogeneous elastic equation, which is then solved to obtain the amplitude of the surface wave generated by the transducer. A reciprocal relationship between the excitation and detection problems is used to obtain the power extracted from the surface wave by an interdigital arrangement of surface electrodes. Measurements made on single crystals of quartz and cadmium sulfide are found to be in good agreement with theoretical predictions. The maximum value of the product (efficiency×fractional bandwidth) for a surface‐wave transducer is calculated. For an interdigital surface‐wave transducer on the basal plane of CdS, the maximum value of this product is found to be 7.8×10−2. It is shown that one can connect linear pairs of surface electrodes in an appropriate binary code so as to obtain high efficiency and large bandwidth transducers.

Accoustic Scattering Parameters of the Electrically Loaded Interdigital Surface Wave Transducer (Correspondence)

Abstract: Acoustic scattering parameters for the interdigital transducer are calculated as a function of electrical loading and frequency using an equivalent circuit model of the interdigital transducer. Measurements of the surface wave scattering parameters at 100 MHz are reported which are in close agreement with theory. Applications of the interdigital array as an efficient reflector of surface waves and as a weak low-reflecting tapping transducer are discussed.

Lithium niobate transducers

Abstract: The specification describes ultrasonic transducers made from single crystal lithium niobate. Five crystal orientations are given for which transducer characteristics are especially favorable.

Piezoelectric generation and detection of ultrasonic surface waves by interdigital electrodes: an electrical equivalent circuit

Abstract: Experiments with voltage pulses applied to an interdigital array of electrodes on the surface of a piezoelectric material suggest a 1-dimensional electrical equivalent circuit valid for generation and detection of ultrasonic surface waves, both transient and sinusoidal. The study also indicates a new method of assessing the piezoelectric coupling coefficient.

Electrode interactions in acoustic surface-wave transducers

Abstract: Results are given which show the importance of acoustic interactions in interdigital surface-wave transducers on piezoelectric materials.

Cylinder-rod dual resonant transducer array

Abstract: This invention pertains to a piezoelectric transducer which employs toroidal piezoelectric transducer elements and a plurality of prismatic piezoelectric rod elements in a unitary assembly. By application of predetermined driving potentials to the aforesaid piezoelectric elements, their acoustic coupling may be varied to produce a low Q combination thereof. Because the basic relationship of the two types of piezoelectric elements is modular in nature, they may also be combined to produce a variety of radiation patterns.

Principles of wideband unidirectional piezoelectric transducers

Abstract: : By interweaving the fingers of an interdigital transducer with an earthed meander line and supplying different voltages, in different phases, to the fingers, a variety of interesting performances may be achieved. Two unidirectional transducers and a diplexing transducer are described as examples of the technique. In order to achieve the performances that theory indicates, a number of technical problems need to be overcome. These problems are pointed out and approaches to their solution are suggested.