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Showing papers on "Interdigital transducer published in 1981"


Journal ArticleDOI
TL;DR: In this article, the electrostatic problem of an arbitrary set of parallel strip electrodes on a dielectric substrate was examined, and a general analytic solution was obtained, but a particular class of problems has not been solved completely.
Abstract: The electrostatic problem of an arbitrary set of parallel strip electrodes on a dielectric substrate is examined, and a general analytic solution obtained. The general solution requires numerical computation to determine some parameten, but a particular class of problems has been solved completely. The solution for the important practical case of an infinite periodic array of electrodes is determined in the limit of the particular solution as the number of electrodes tends to infinity. W

44 citations


Journal ArticleDOI
TL;DR: In this article, an arched interdigital transducer was devised for acoustic imaging uses, where two kinds of acoustic beams are radiated into water from the transducers, one of which is radiated at a constant angle independent of the frequency change.
Abstract: An arched interdigital transducer has been devised for acoustic imaging uses. Two kinds of acoustic beams are radiated into water from the transducer, one of which is radiated at a constant angle independent of the frequency change. The other has a frequency‐dependent radiation angle. The two beams follow conical paths and come to a focus on the axis of the arc. The arched transducer with 45 ° aperture angle, consisting of 10 finger pairs, has a conversion loss of about 10 dB and about 150‐μm beamwidth for 3 dB down values, at 22.7 MHz.

22 citations


Proceedings ArticleDOI
01 Jan 1981
TL;DR: Theoretical predictions of the velocity and attenuation of leaky surface waves and surface skimming bulk waves on a free surface and under a metal film and a water film are presented in this article.
Abstract: The high value of K2 associated with shear horizontal waves launched by an interdigital transducer (IET) on 41' rotated Y-cut Lithium Niobate (an SSBW cut) makes the launching and propagation of these waves of particular interest. Theoretical predictions of the velocity and attenuation of leaky surface waves and surface skimming bulk waves on a free surface and under a metal film and a water film are presented. Experimental results confirm the predicted slowing of the Leaky wave by about 10% under metal and 5% under water. Experiments on propagation under a periodic metal grating reveal that only a single mode propagates if it is fed with a symmetric wave. If fed with an antisymmetric wave severe attenuation occurs. Preliminary results on the behaviour of ininterdigital transducer are presented.

16 citations


Journal ArticleDOI
TL;DR: In this article, a theory based on Fourier analysis of light diffracted from a grating interacting with a surface acoustic wave (SAW) is developed, which produces an amplitude modulation of light in the 0 and ± 1 orders of diffraction with a depth of modulation proportional to the SAW amplitude.
Abstract: The opitcal detection of surface acoustic waves (SAW) using stationary reference gratings (SRG) on a substrate is considered. The theory based on Fourier analysis of light diffracted from a grating interacting with a SAW is developed. As shown theoretically and confirmed experimentally the interaction of light with SAW and SRG produces an amplitude modulation of light in the 0 and ±1 orders of diffraction with a depth of modulation proportional to the SAW amplitude. The detection of SAW amplitudes on the order of 10−3 A was predicted by theoretical analysis and confirmed by experimental measurements with a bandwidth of detection of 1 kHz. It was demonstrated that second harmonics of comparable amplitudes could also be detected. Measurements of the amplitude of SAW reflected from the free edge of the substrate, as well as SAW reflected from an interdigital transducer, were also demonstrated. It was shown that the SRG method of optical detection can be used for signal processing, for smoothly varying delay,...

16 citations



Patent
15 Dec 1981
TL;DR: A group-arranged type unidirectional surface acoustic wave transducer was proposed in this paper, where the center-to-center distance between the electrodes is made equal to an integral number of wavelengths plus three quarter wavelengths.
Abstract: A group-arranged type unidirectional surface acoustic wave transducer, which includes, in combination, groups of interdigital electrodes wherein the center-to-center distance between the electrodes is made equal to an integral number of wavelengths plus a quarter wavelength and further groups of interdigital electrodes wherein the center-to-center distance between the electrodes is made equal to an integral number of wavelengths plus three quarter wavelengths. According to the present invention, there is also provided a unidirectional surface acoustic wave device which can be employed as a filter by changing the frequency-amplitude characteristic of the surface acoustic wave.

12 citations


Patent
Kaempf Erich1
20 May 1981
TL;DR: In this paper, the metal coating of a contact foil is connected to a strip-shaped piezoelectric body, and the body is subsequently subdivided, in which the parts of the contact foil overhanging at the ends of the transducer elements are separated into contact tabs for individual transducers, with one tab connected to control conductor and the other tab forming electrically conducting bridges for the transducers.
Abstract: A method for manufacturing an ultrasonic transducer arrangement with groups of jointly controlled transducer elements, in which the metal coating of a contact foil is connected to a strip-shaped piezoelectric body, and the piezoelectric body, with the metal coating, is subsequently subdivided, in which the parts of the contact foil overhanging at the ends of the transducer elements are separated into contact tabs for individual transducer groups at both ends with one tab connected to a control conductor and the other tab forming electrically conducting bridges for the transducer elements of its transducer group. The bridges increase the operating reliability of the transducer arrangement produced, in that each transducer element is provided with an electrical lead at both its ends.

10 citations


Patent
David Errol Bower1
03 Dec 1981
TL;DR: In this article, the authors proposed a surface acoustic wave filter using a length-weighted interdigital transducer (T1) on one side of which are bus bar parts (BP1, BP2) which are within the transducers acoustic aperture and are inclined at an acute angle to the propagation path.
Abstract: A surface acoustic wave filter includes a length-weighted interdigital transducer (T1) on one side of which are bus bar parts (BP1, BP2) which are within the transducer acoustic aperture (A), are inclined at an acute angle to the propagation path (P) and which closely follow the major lobe (L1). These bus bar parts each have a width (W) along the propagation path (P) defined by 2W=nλ/2 where n is an odd integer and λ is the wavelength of surface acoustic waves at substantially the maximum amplitude response frequency of the transducer (T1). The components of the surface acoustic waves reflected from the two edges of each inclined bus bar part along the propagation path, that is to say the component reflected waves (SW1) reflected from the edge closest to the overlap envelope and the component reflected waves (SW2) reflected from the edge which forms part of one end of the transducer, are in antiphase at that maximum response frequency and so spurious signals due to the component reflected waves (SW1 and SW2) at that frequency are substantially suppressed.

10 citations


Patent
03 Dec 1981
TL;DR: In this article, the phase velocity of the surface acoustic wave of the piezoelectric film is smaller than that of the non-pizzalectric plate and the interdigital electrode has a split structure.
Abstract: A surface acoustic wave transducer has a multilayered substrate which is made of a nonpiezoelectric plate which has a surface which is coated with a piezoelectric film, and has an interdigital electrode which is disposed on or under the surface of the piezoelectric film. The interdigital electrode has a split structure and the phase velocity of the surface acoustic wave of the piezoelectric film is smaller than that of the nonpiezoelectric plate.

9 citations


Patent
16 Nov 1981
TL;DR: In this paper, a separated substrate acoustic wave device with an active piezoelectric substrate and a separate base substrate was proposed. But the active substrate was not used to detect the acoustic wave propagation.
Abstract: A separated substrate acoustic wave device having an active piezoelectric substrate and a separate base substrate. Input and output transducers are mounted upon the base substrate. The active substrate, which includes grooved-array reflectors in the case of resonators, is mounted opposite the base substrate so that it does not contact the transducer electrodes and further so that electric fringing fields generated in the transducers will induce an acoustic wave due to the piezoelectric effect in the active substrate. Similarly, acoustic waves propagating in the active piezoelectric substrate will have an associated electric field which induces an electrical signal in the transducer permitting detection of the acoustic waves propagating in the active substrate.

9 citations


Patent
21 Aug 1981
TL;DR: In this article, the rotary Y-cut angle is set counterclockwise in a range of -43 deg.-52 deg. in terms of the axis X for a quartz substrate which transmits the slip wave.
Abstract: PURPOSE:To obtain an inexpensive resonator which has the excellent temperature characteristics and is insensitive to the contaimination on the surface, by setting the thickness of film at a prescribed value for a multipair interdigital transducer electrode provided on a quartz substrate that transmits the slip wave. CONSTITUTION:The rotary Y-cut angle is set counterclockwise in a range of -43 deg.--52 deg. in terms of the axis X for a quartz substrate which transmits the slip wave. The bus bar electrodes 2 and 3 are formed with Al on the substrate 1 in the direction of the axis Z'. These electrodes are so extended as to cross interdigital electrode fingers 4 and 5 alternately. The ratio h/lambda betwen the film thickness (h) of the extended electrode and the propagating slip wavelength lambda is regulated to >=2%, and the number of pairs of electrodes 4 and 5 is regulated to 800+ or -200. At the same time, the w/lambda ratio is regulated to 8-15 between the cross length (w) of the electrode finger and the wavelength lambda. As a result, the right-under-electrode enclosing effect is improved for the oscillating energy of the slip wave along with excellent temperature characteristics. Thus an inexpensive resonator, which is insensitive to the surface contamination and the aging and oscillates the high frequency up to about 1GHz with the basic wave and with virtually no spuriousness and high Q.

Patent
22 Apr 1981
TL;DR: In this article, a bus bar part was constructed by stacking an electrode finger end part and a single-layer bas bar much thicker than the electrode fingers on a piezoelectric substrate.
Abstract: PURPOSE:To reduce the conductor resistance of a bus bar part by constituting an input-output interdigital transducer by stacking an electrode finger end part and a single-layer bas bar much thicker than the electrode fingers. CONSTITUTION:On piezoelectric substrate 1, cross electrode fingers 2 are formed. Next, single-layer bus bars 3 are formed which are much thicker than cross electrode fingers 2 and less in natural resistance.

Patent
06 Apr 1981
TL;DR: In this paper, a piezoelectric transducer was used to transmit or receive ultrasonic waves in a medium (6) whose acoustic impedance is similar to that of water, and can be used, for example, in the medical examinations using echography methods.
Abstract: This piezoelectric transducer is intended to transmit or receive ultrasonic waves in a medium (6) whose acoustic impedance is similar to that of water, and can be used, for example, in the medical examinations using echography methods. The piezoelectric transducer has a large bandwidth, and contains a piezoelectric polymer active component (1) inserted between two electrodes (4a,4b) which form a capacitor. The active component (1) is excited in a transverse vibration mode. One of its faces (1a) is coupled to the medium (6) which receives or transmits ultrasonic waves. Its other face (1b) is coupled to a reflective medium (30). The impedance of the reflective medium (30) is appreciably lower than the impedance of the piezoelectric polymer (1). The active component (1) thickness is half a wavelength at the centre frequency of the transducer.

Patent
25 Jun 1981
TL;DR: In this paper, an acoustic surface wave device is disclosed for generating an output signal that is the phase-conjugate of the input signal to the device, and a second inter-digital transducer is disposed on the surface of the piezoelectric substrate between the first interdigital transducers and the semiconductor material.
Abstract: An acoustic surface wave device is disclosed for generating an output signal that is the phase-conjugate of the input signal to the device. Disposed on the piezoelectric substrate is a first interdigital transducer for receiving a modulated input signal having a carrier center frequency f 1 and for converting the input signal to an input acoustic wave. A semiconductor material is disposed over the surface of the piezoelectric substrate. A second interdigital transducer is disposed on the surface of the piezoelectric substrate between the first interdigital transducer and the semiconductor material. A standing wave at frequency f 1 is generated by counterpropagating pump waves in the nonlinear acoustic wave interaction region in the area of the semiconductor material. The modulated input acoustic wave interacts with the counterpropagating pump waves in the nonlinear interaction region to generate an output signal on the output of the second interdigital transducer that is the phase-conjugate of the input signal.

Journal ArticleDOI
TL;DR: In this article, the sound velocity difference between two delayed signals passed through two liquid cavities, which is converted to a dc voltage via a phase comparating circuit, corresponds to the phase difference.
Abstract: The theory and experimental results for a method of measuring the sound velocity difference in two liquids are described. The compressional wave is radiated into a liquid from an interdigital transducer. The substrate surface without the interdigital electrodes is not in contact with the liquid. The phase difference between two delayed signals passed through two liquid cavities, which is converted to a dc voltage via a phase comparating circuit, corresponds to the sound velocity difference. An experimental confirmation of the propriety of the values obtained by the method is given in water with different temperatures.

Journal ArticleDOI
TL;DR: In this article, the authors present theoretical and experimental results for the reflection characteristics of open metal strip arrays, and derive the expression of the reflection coefficient in a closed form by the image parameter theory.
Abstract: This paper presents theoretical and experimental results for the reflection characteristics of open metal strip arrays. In the analysis, the equivalent circuit model for an interdigital transducer is applied, and the expression of the reflection coefficient is derived in a closed form by the image parameter theory. In the investigations on the substrate of LiNbO3 (128° rot. Y, X-prop.), a good agreement between the calculated and experimental results is obtained.

Journal ArticleDOI
TL;DR: In this paper, a new type of transducer was obtained for exciting only tangential displacement of a wave using an interdigital transducers, which utilises a ferroelectric medium with a distributed polarisation caused by interdigital electrodes.
Abstract: A new type of transducer has been obtained for exciting only tangential displacement of a wave using an interdigital transducer. The device utilises a ferroelectric medium with a distributed polarisation caused by interdigital electrodes. An exciting interdigital electrode is located at the optimum position with respect to the polarisation pattern. Experimental results obtained with one such transducer are presented.

Proceedings ArticleDOI
01 Jan 1981

Proceedings ArticleDOI
01 Jan 1981
TL;DR: In this article, an SAW transducer for NDE applications utilizing bulk-to-surface mode conversion is proposed and studied in theory and experiment, where an interdigital electrode on a piezoelectric block is used to generate and detect the angle beam of bulk waves.
Abstract: A new SAW transducer for NDE applications utilizing bulk-to-surface mode conversion is proposed and studied in theory and experiment. In this transducer an interdigital electrode on a piezoelectric block is used to generate and detect the angle beam of bulk waves. In order to reduce too large perturbation of the piezoelectric block against the SAW guide, a solid coupling layer is bonded to the block. Mode conversion characteristics of the transducer are theoretically analyzed taking account of the leaky wave phenomena. It is demonstrated experimentally that radial (diverging and converging) SAW and steerable SAW transducers can be easily realized using the interdigital transducer with curved fingers. An application of the transducer to SAW velocity measurements is also described.

Proceedings ArticleDOI
01 Jan 1981
TL;DR: In this article, a modified sputter gun was used to provide electrical isolation between the source and the substrate allowing the use of high power density without subjecting the substrates to electron bombardment.
Abstract: Aluminum-nitride films have been deposited on various substrate utilizing a modified sputter gun. It provides electrical isolation between the source and the substrate allowing the use of high power density without subjecting the substrates to electron bombardment. Any electron leakage on the axis is trapped by additional magnetic field. pletely free f rom electron bombardment. A very strong magnetic field makes it possible to sputter below lm Torr. This high vacuum sputtering improves x-ray (002)-peak intensity, surface smoothness, film color, transparency, and deposition rate. The deposition rate of the sputter gun is as high as 2.4 m/hr at input power of 300 W. This report will focus on the quality of acoustic and optical properties. The insertion loss of the A1N film (h/h = 0.35) on Corning 0211 glass is 39 dB at frequency of 193.4 MHz. The center to center propagation distance is 10 mm. The design parameters of the interdigital transducer are as follows: finger pair 12, wavelength 23.3 ilm, aperture 1.0 mm. The growing A1N film is com

Journal ArticleDOI
TL;DR: In this paper, the SAW dispersive delay line whose temperature coefficients of the delay time, phase and frequency are dependent on the substrate material and the frequency-dispersive characteristics is discussed.
Abstract: The SAW dispersive delay line is used extensively for signal processing, such as pulse compressor and spread spectrum system. In the filter and delay line using the ordinary interdigital transducer, the temperature coefficients of the delay time, phase and frequency are identical and depend on the substrate material. In this paper, we discuss the SAW dispersive delay line whose temperature coefficients of the delay time, phase and frequency are dependent on the substrate material and the frequency-dispersive characteristics. The temperature characteristics can be improved by optimizing the dispersion characteristics. The zero temperature coefficient can be realized even if the substrate temperature coefficient is impractical. The design of the dispersive delay line is proposed with consideration of the temperature characteristics.