All issues
Volume 36, Issue 11
Displaying 1-9 of 9 articles from this issue
- |<
- <
- 1
- >
- >|
-
Toshihiro Kojima, Tatsuo SuzukiArticle type: Article
1980 Volume 36 Issue 11 Pages 539-548
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSThe admittance parameters Y_<ij> of the uniform types of the single and double IDT (Interdigital Transducer) are derived in closed form. In these derivations, the image parameter theory is used, and the reflections due to the discontinuity of acoustic wave impedances between the electroded and nonelectroded regions are taken into account. By these simple expressions of Y_<ij>, the driving point admittance Y^<(E)> of IDT and the reflection coefficient Γ_R of IDT as a reflector are derived in closed form. Next, many numerical calculations and experiments about Y^<(E)> and Γ_R of both types of IDT are performed with LiNbO_3 in order to investigate their characteristics. In particular, Γ_R of the IDT reflectors are presented under some kinds of electrical loads. From these theoretical and experimental investigations the followings are cleared : (1) The differences of characteristics for Y^<(E)> and Γ_R between the single and double electrodes escalate conspicuously according as finger pairs increase. (2) The theoretical values obtained here about the double electrode agree with those obtained from the model neglecting the second order effects. (3) The effective impedance discontinuity factor τ_e_f_f evaluated from the experiments on Y^<(E)> is approximated by the velocity discontinuity factor τ_v, while τ_e_f_f from the experiments on Γ_R is somewhat less than τ_v. (4) IDT reflectors having large |Γ_R|(>0. 9) are obtained easily by small number of finger pairs (N≦30).View full abstractDownload PDF (1081K) -
Masao Takeuchi, Hiroshi ShimizuArticle type: Article
1980 Volume 36 Issue 11 Pages 549-557
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSAcoustic grating couplers for mode conversion between bulk and surface waves are promising for intense surface acoustic wave (SAW) generation in the frequency rarge from VHF to UHF. In this paper, the performance of the grating couplers is theoretically analyzed on the basis of the leaky wave concept and the coupled mode theory, and the following points are clarified : 1) the mode conversion efficiency to be expected, 2) the dependence of the efficiency on the coupling length, 3) the difference between P-wave coupling and S-wave coupling to SAW, 4) the frequency characteristics of conversion efficiency. Also, the attenuation constant and the distribution factor, wihch determine the optimum coupling length and the conversion efficiency, are numerically calculated for several grating configurations.View full abstractDownload PDF (1005K) -
Nobuyuki Endoh, Naoki Kawai, Atsuhiko Katoh, Motoyoshi OkujimaArticle type: Article
1980 Volume 36 Issue 11 Pages 558-564
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSA new imaging method has been developed which is capable of obtaining high resolutions both in lateral and longitudinal directions. It is very important to minimize the number of the receivers for practical use, because many electronic circuits and a large memory capacity are required. Reduction of the number of receivers, however, may cause spurious images. The magnitude of the spurious image is in nearly inverse proportion to the number of receivers. To solve this problem, the arrangement of the receiver array is examined. It is expected that an image which has a low side lobe level will be obtained if an array of 44 receivers arranged on 4 concentric circles is used. For reconstructing image, some signal processing methods such as multiplication or polarity correlation are examined. Experiments are carried out in a water bath with some model targets. A clear image of 3 steel balls of 10 mm diameter can be obtained.View full abstractDownload PDF (837K) -
Shuichiro YamamizuArticle type: Article
1980 Volume 36 Issue 11 Pages 565-571
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSA direct measuring method for acoustic characteristics of thin-layered ultrasonic bonding materials is proposed. In this method, the knowledge of material constants such as density and velocity is not needed. The principle of the method is to measure the transmission and reflection wave intensity from the equivalent transmission lines composed of thin-layered bonding material which is sandwiched by fused quartz buffers. Then, by exciting one of the buffers with LiNbO_3 or ZnO film ultrasonic transducer, the transmission and reflection wave from bonding layer are measured. For different thicknesses of the bonding material, a series of measured data is obtained and the comparison of the data with theoretical curves determined the acoustic impedance and velocity of the bonding material. The ultrasonic attenuation constant of bonding material as a function of frequency is also determined by measuring the transmission and reflection wave intensity in the same manner as acoustic impedance measurement. The measuring method for rosin and stilben is described as an example and their acoustic characteristics are presented.View full abstractDownload PDF (783K) -
Noriyoshi ChubachiArticle type: Article
1980 Volume 36 Issue 11 Pages 572-575
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSDownload PDF (547K) -
Masao IdeArticle type: Article
1980 Volume 36 Issue 11 Pages 576-580
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSDownload PDF (799K) -
Shin-ichi Hanamura, Masao Kumano, Masaaki ShishidoArticle type: Article
1980 Volume 36 Issue 11 Pages 581-585
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSDownload PDF (963K) -
Shoichi Ishiwata, Kenshi Shirai, Hiroyuki TakejiArticle type: Article
1980 Volume 36 Issue 11 Pages 586-589
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSDownload PDF (615K) -
Katashi HazamaArticle type: Article
1980 Volume 36 Issue 11 Pages 590-592
Published: November 01, 1980
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSDownload PDF (352K)
- |<
- <
- 1
- >
- >|