Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495542
M. Sharif, M. Schwab, D. Chen, C. Hartmann
The conventional coupled resonator filters, widely used in mobile communication systems, usually work with unbalanced termination conditions in both input and output electrical ports. However, there are increasing demands from systems engineers to have compact SAW filters which are able to operate with differential input and/or output termination. To meet these demands, two kinds of new innovative structures have been developed. In this paper the basic idea on which the new innovative structures are based are first discussed. This is followed by the presentation of the new structures in detail as experimental devices. The first is a 6-pole transversely coupled resonator filter at 150 MHz with a more than 100 kHz of 3 dB working bandwidth and very low shape factor (the transition bandwidth from -3 dB to -35 dB is less than 40 kHz), built on 34/spl deg/YX-quartz. It works with both input and output terminals in differential conditions. The other is a longitudinally coupled resonator filter built on 36/spl deg/YX-LiTaO/sub 3/ substrate and working at 860 MHz with a fractional bandwidth of about 1.5%. It operates with unbalanced input but differential output.
{"title":"Coupled resonator filters with differential input and/or differential output","authors":"M. Sharif, M. Schwab, D. Chen, C. Hartmann","doi":"10.1109/ULTSYM.1995.495542","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495542","url":null,"abstract":"The conventional coupled resonator filters, widely used in mobile communication systems, usually work with unbalanced termination conditions in both input and output electrical ports. However, there are increasing demands from systems engineers to have compact SAW filters which are able to operate with differential input and/or output termination. To meet these demands, two kinds of new innovative structures have been developed. In this paper the basic idea on which the new innovative structures are based are first discussed. This is followed by the presentation of the new structures in detail as experimental devices. The first is a 6-pole transversely coupled resonator filter at 150 MHz with a more than 100 kHz of 3 dB working bandwidth and very low shape factor (the transition bandwidth from -3 dB to -35 dB is less than 40 kHz), built on 34/spl deg/YX-quartz. It works with both input and output terminals in differential conditions. The other is a longitudinally coupled resonator filter built on 36/spl deg/YX-LiTaO/sub 3/ substrate and working at 860 MHz with a fractional bandwidth of about 1.5%. It operates with unbalanced input but differential output.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123481729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495845
S. Wu, J. Reyner, K. Shung, H. Routh
Power Doppler imaging was used in this study to detect flow turbulence and the effect of flow shear on blood cell aggregation. Porcine RBC saline suspensions of different hematocrits were circulated in a steady flow loop containing a 318" ID tube. A mesh screen, formed by gold-plated needles was installed in the tube to generate now disturbance. It has previously been shown that flow disturbance can increase ultrasonic echogenicity and Doppler power. In this study, images were taken with a power Doppler scanner and analyzed with a digital frame grabber to investigate the influence of the turbulence on Doppler power at different hematocrits, flow speeds and positions relative to the mesh screen. The increase of intensity of the Doppler images indicates increase of Doppler power and can aid in detecting the flow disturbance behind arterial stenosis. A second study, on porcine whole blood was undertaken in a steady flow loop containing 3/16" ID tube with an additional reservoir and shunt in the loop so that the inflow and outflow speed can be varied. Doppler power imaging showed a difference of intensity between inflow and outflow as the flow (or shear) rate was changed This difference could help in discriminating small arteries and veins.
{"title":"A study on the feasibility of using power level for detection of turbulence and vessel differentiation in Doppler power imaging","authors":"S. Wu, J. Reyner, K. Shung, H. Routh","doi":"10.1109/ULTSYM.1995.495845","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495845","url":null,"abstract":"Power Doppler imaging was used in this study to detect flow turbulence and the effect of flow shear on blood cell aggregation. Porcine RBC saline suspensions of different hematocrits were circulated in a steady flow loop containing a 318\" ID tube. A mesh screen, formed by gold-plated needles was installed in the tube to generate now disturbance. It has previously been shown that flow disturbance can increase ultrasonic echogenicity and Doppler power. In this study, images were taken with a power Doppler scanner and analyzed with a digital frame grabber to investigate the influence of the turbulence on Doppler power at different hematocrits, flow speeds and positions relative to the mesh screen. The increase of intensity of the Doppler images indicates increase of Doppler power and can aid in detecting the flow disturbance behind arterial stenosis. A second study, on porcine whole blood was undertaken in a steady flow loop containing 3/16\" ID tube with an additional reservoir and shunt in the loop so that the inflow and outflow speed can be varied. Doppler power imaging showed a difference of intensity between inflow and outflow as the flow (or shear) rate was changed This difference could help in discriminating small arteries and veins.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116795203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495598
S. Makarov, E. Chilla, H.-J. Frohlich
For the determination of the mechanical properties of thin films the inverse problem of the surface acoustic wave (SAW) propagation has to be solved by using the phase velocity dispersion for input data. We have analysed the numerical solution of the inverse problem by calculating a two-dimensional error field of least-squares fits. The shape of the error field is a function of arbitrary elastic parameters with respect to their exact values. Various isotropic films deposited on Y-cut LiNbO/sub 3/ were considered. It was found that by the use of the dispersion of two independent SAW modes the elastic parameters of an isotropic thin film can be determined with high accuracy.
{"title":"Determination of elastic constants of thin films by dispersion of various SAW modes","authors":"S. Makarov, E. Chilla, H.-J. Frohlich","doi":"10.1109/ULTSYM.1995.495598","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495598","url":null,"abstract":"For the determination of the mechanical properties of thin films the inverse problem of the surface acoustic wave (SAW) propagation has to be solved by using the phase velocity dispersion for input data. We have analysed the numerical solution of the inverse problem by calculating a two-dimensional error field of least-squares fits. The shape of the error field is a function of arbitrary elastic parameters with respect to their exact values. Various isotropic films deposited on Y-cut LiNbO/sub 3/ were considered. It was found that by the use of the dispersion of two independent SAW modes the elastic parameters of an isotropic thin film can be determined with high accuracy.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123966600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495805
S. Holm, B. Elgetun
A method is presented which optimizes weights of general planar 1D and 2D symmetric full and sparse arrays. The objective is to find a weighting of the array elements which gives the minimum sidelobe level of the array pattern in a specified region-the stop-band. The sidelobe level is controlled on a discrete set of points from this region. The method minimizes the Chebyshev norm of the sidelobe level. The method is based on linear programming and is solved with the simplex method. The method removes the large fluctuation in sidelobe level which characterizes random sparse arrays. Examples of optimal weighted 1D and 2D planar arrays are presented.
{"title":"Optimization of the beampattern of 2D sparse arrays by weighting","authors":"S. Holm, B. Elgetun","doi":"10.1109/ULTSYM.1995.495805","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495805","url":null,"abstract":"A method is presented which optimizes weights of general planar 1D and 2D symmetric full and sparse arrays. The objective is to find a weighting of the array elements which gives the minimum sidelobe level of the array pattern in a specified region-the stop-band. The sidelobe level is controlled on a discrete set of points from this region. The method minimizes the Chebyshev norm of the sidelobe level. The method is based on linear programming and is solved with the simplex method. The method removes the large fluctuation in sidelobe level which characterizes random sparse arrays. Examples of optimal weighted 1D and 2D planar arrays are presented.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"19 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125761507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495788
P. VanBaren, J. Kluiwstra, R. Seip, Y. Zhang, E. Ebbini, C. Cain
Ultrasound has proven to be an effective modality for inducing hyperthermia for cancer therapy because of the spatial control of the SAR that may be achieved. The use of phased-array ultrasound applicators provides additional benefits because the ultrasound field may be changed rapidly (at electronic speeds) and may be used to focus the field at several locations simultaneously. To obtain these qualities, large apertures with element counts exceeding several hundred are needed. However, with the increase in the number of elements, both the control and fabrication process involve greater complexity. Therefore the construction of phased array systems, especially those using geometric focusing to increase intensity gain, has proven technically difficult. In order to avoid complex machining and mounting procedures, a modular approach to array construction has been developed. To test this approach, phased arrays with 192 and 512 elements have been designed, fabricated and characterized in the authors' laboratory. These arrays are composed of flat panels arranged to approximate a spherically shaped aperture. Experimental acoustic measurements for both arrays are presented and compared with computer simulations, showing good agreement. In addition, experimental results using these arrays, in conjunction with a control algorithm developed in the authors' lab, to induce and maintain hyperthermia in in vivo canine thigh muscle are presented. These results demonstrate the flexibility of such applicators, and the control which they can achieve over the SAR field.
{"title":"2D large aperture ultrasound phased arrays for hyperthermia cancer therapy: design, fabrication and experimental results","authors":"P. VanBaren, J. Kluiwstra, R. Seip, Y. Zhang, E. Ebbini, C. Cain","doi":"10.1109/ULTSYM.1995.495788","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495788","url":null,"abstract":"Ultrasound has proven to be an effective modality for inducing hyperthermia for cancer therapy because of the spatial control of the SAR that may be achieved. The use of phased-array ultrasound applicators provides additional benefits because the ultrasound field may be changed rapidly (at electronic speeds) and may be used to focus the field at several locations simultaneously. To obtain these qualities, large apertures with element counts exceeding several hundred are needed. However, with the increase in the number of elements, both the control and fabrication process involve greater complexity. Therefore the construction of phased array systems, especially those using geometric focusing to increase intensity gain, has proven technically difficult. In order to avoid complex machining and mounting procedures, a modular approach to array construction has been developed. To test this approach, phased arrays with 192 and 512 elements have been designed, fabricated and characterized in the authors' laboratory. These arrays are composed of flat panels arranged to approximate a spherically shaped aperture. Experimental acoustic measurements for both arrays are presented and compared with computer simulations, showing good agreement. In addition, experimental results using these arrays, in conjunction with a control algorithm developed in the authors' lab, to induce and maintain hyperthermia in in vivo canine thigh muscle are presented. These results demonstrate the flexibility of such applicators, and the control which they can achieve over the SAR field.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125993282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495655
G. Weaver, V. Bright, J. Kosinski
Dilithium tetraborate is a promising piezoelectric material for both bulk acoustic wave and surface acoustic wave devices. In order to design temperature compensated devices, it is necessary to know the behavior of the material constants with respect to temperature variations. In this paper, the first and second order temperature coefficients of the material constants c/sub 11//sup E/, c/sub 12//sup E/, c/sub 66//sup E/, and e/sub 15/ of Li/sub 2/B/sub 4/O/sub 7/ have been measured over a temperature range of 20/spl deg/C to 150/spl deg/C. An improved resonator method was used to measure the fundamental zero mass loading antiresonance frequencies of selected pure-mode orientations of Li/sub 2/B/sub 4/O/sub 7/. Material constants extraction was performed using a linear least squares matrix method. The resulting material constant curves were fit with a third order power series to obtain their corresponding temperature coefficients. The calculated first order temperature coefficients of the material constants show reasonable agreement with previously published values. The calculated second order coefficients do not agree well with the previously published values, and may help to resolve the large discrepancies between predicted and measured behavior of Li/sub 2/B/sub 4/O/sub 7/ resonators.
{"title":"Temperature coefficients of selected material constants of dilithium tetraborate (Li/sub 2/B/sub 4/O/sub 7/)","authors":"G. Weaver, V. Bright, J. Kosinski","doi":"10.1109/ULTSYM.1995.495655","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495655","url":null,"abstract":"Dilithium tetraborate is a promising piezoelectric material for both bulk acoustic wave and surface acoustic wave devices. In order to design temperature compensated devices, it is necessary to know the behavior of the material constants with respect to temperature variations. In this paper, the first and second order temperature coefficients of the material constants c/sub 11//sup E/, c/sub 12//sup E/, c/sub 66//sup E/, and e/sub 15/ of Li/sub 2/B/sub 4/O/sub 7/ have been measured over a temperature range of 20/spl deg/C to 150/spl deg/C. An improved resonator method was used to measure the fundamental zero mass loading antiresonance frequencies of selected pure-mode orientations of Li/sub 2/B/sub 4/O/sub 7/. Material constants extraction was performed using a linear least squares matrix method. The resulting material constant curves were fit with a third order power series to obtain their corresponding temperature coefficients. The calculated first order temperature coefficients of the material constants show reasonable agreement with previously published values. The calculated second order coefficients do not agree well with the previously published values, and may help to resolve the large discrepancies between predicted and measured behavior of Li/sub 2/B/sub 4/O/sub 7/ resonators.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128651931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495705
V. S. Ardebili, A. Sinclair
The angular spectrum of an acoustic lens of large aperture angle is calculated by integration of the field directly on the surface of the lens cavity. In contrast to the customary method, where the distribution of the acoustic field on the flat aperture of the lens is assumed to be known, the new method makes no such assumptions. The calculated V(z) based on this angular spectrum shows good agreement with published experimental data. Also, the distribution of the reflected field on the surface of a spherical lens throughout a typical z scan is calculated. This gives new insight into ray models of an acoustic lens. Implications for the case of high attenuation, low speed coupling fluids for use in micro-mechanical characterization of polymers are explored.
{"title":"A new angular spectrum approach for modelling the acoustic microscope response with high attenuation coupling fluids","authors":"V. S. Ardebili, A. Sinclair","doi":"10.1109/ULTSYM.1995.495705","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495705","url":null,"abstract":"The angular spectrum of an acoustic lens of large aperture angle is calculated by integration of the field directly on the surface of the lens cavity. In contrast to the customary method, where the distribution of the acoustic field on the flat aperture of the lens is assumed to be known, the new method makes no such assumptions. The calculated V(z) based on this angular spectrum shows good agreement with published experimental data. Also, the distribution of the reflected field on the surface of a spherical lens throughout a typical z scan is calculated. This gives new insight into ray models of an acoustic lens. Implications for the case of high attenuation, low speed coupling fluids for use in micro-mechanical characterization of polymers are explored.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127114500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495662
H. Nishino, Y. Tsukahara, H. Cho, H. Sato, K. Yamanaka
Excitation of high-frequency bulk acoustic waves (BAW) using scanning interference fringes (SIF) is presented. The SIF are produced by intersecting two coherent laser beams with different frequencies on an opaque specimen. It is possible to generate unidirectional BAW which propagate into the specimen by this method. Propagation direction of the BAW is determined by the phase-matching condition between the SIF and the wave front of the BAW at the surface, which could be controlled by incident angles of laser beams. The principle and verification of this method are briefly described in the first part. Application to the BAW velocity measurement was introduced and was experimentally verified using Si/sub 3/N/sub 4/ specimen. Acoustical imagings taken by the BAW generation method were also shown in the last part.
{"title":"Unidirectional bulk acoustic wave excitation by scanning interference fringes and its application to acoustical imagings","authors":"H. Nishino, Y. Tsukahara, H. Cho, H. Sato, K. Yamanaka","doi":"10.1109/ULTSYM.1995.495662","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495662","url":null,"abstract":"Excitation of high-frequency bulk acoustic waves (BAW) using scanning interference fringes (SIF) is presented. The SIF are produced by intersecting two coherent laser beams with different frequencies on an opaque specimen. It is possible to generate unidirectional BAW which propagate into the specimen by this method. Propagation direction of the BAW is determined by the phase-matching condition between the SIF and the wave front of the BAW at the surface, which could be controlled by incident angles of laser beams. The principle and verification of this method are briefly described in the first part. Application to the BAW velocity measurement was introduced and was experimentally verified using Si/sub 3/N/sub 4/ specimen. Acoustical imagings taken by the BAW generation method were also shown in the last part.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128919000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495658
M. F. Leach, D. Goldsack, H.J. Chartrand
A judicious choice of factors considered essential for producing musical sounds has led to an experimental procedure which creates musical sands from previously silent ones. An analysis of this procedure provides evidence that the composition of the sand grains aid the condition of the grain surfaces play a delicate role. X-ray fluorescence tests have revealed that the best musical sands are primarily quartzitic. Repeated wetting and drying action allows silica to abrade softer feldspars and this forms fine dust which is removed by milling and by renewing the water. It also appears that, as water dries on the grains of sand, the surfaces are coated with an extremely thin film of salts and water in an amorphous silica layer. Preliminary infrared spectroscopic studies of the surface of different types of booming and singing sands are reported. These results lead to the conclusion that the music is generated by the rubbing together of the surfaces of millions of grains of quartz with particular composition and surface characteristics. Knowledge of the musical sand phenomenon may be useful in understanding the mechanics of many other granular system and numerous other processes in geology and technology.
{"title":"Grain composition and surface characteristics of musical sand","authors":"M. F. Leach, D. Goldsack, H.J. Chartrand","doi":"10.1109/ULTSYM.1995.495658","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495658","url":null,"abstract":"A judicious choice of factors considered essential for producing musical sounds has led to an experimental procedure which creates musical sands from previously silent ones. An analysis of this procedure provides evidence that the composition of the sand grains aid the condition of the grain surfaces play a delicate role. X-ray fluorescence tests have revealed that the best musical sands are primarily quartzitic. Repeated wetting and drying action allows silica to abrade softer feldspars and this forms fine dust which is removed by milling and by renewing the water. It also appears that, as water dries on the grains of sand, the surfaces are coated with an extremely thin film of salts and water in an amorphous silica layer. Preliminary infrared spectroscopic studies of the surface of different types of booming and singing sands are reported. These results lead to the conclusion that the music is generated by the rubbing together of the surfaces of millions of grains of quartz with particular composition and surface characteristics. Knowledge of the musical sand phenomenon may be useful in understanding the mechanics of many other granular system and numerous other processes in geology and technology.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128938434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-07DOI: 10.1109/ULTSYM.1995.495590
C. Thoma, Y. Hahn
The design and fabrication of interdigital transducers with metallic fingers on piezoelectric substrates requires accurate values of velocity shifts and reflection coefficients caused by the mechanical and electrical loading of the fingers. We describe a simple and reliable method of determining electric reflection and velocity shifts as well as mechanical velocity shifts to first order in h//spl lambda/ for transducers with an anisotropic substrates. We calculate SAW velocities and wavefunctions (displacements and potential) for various substrates with one thin metallic layer. A simple multiplication of the resulting material constants with the appropriate geometrical factor yields the desired SAW parameters. An analogous procedure for the mechanical reflection coefficient is being sought. We present results for many standard SAW substrates and crystal orientations with a metallic overlay, and compare with other first order treatments and some experimental results presently available.
{"title":"A simple determination of first order velocity shifts and reflection coefficients for periodic IDTs","authors":"C. Thoma, Y. Hahn","doi":"10.1109/ULTSYM.1995.495590","DOIUrl":"https://doi.org/10.1109/ULTSYM.1995.495590","url":null,"abstract":"The design and fabrication of interdigital transducers with metallic fingers on piezoelectric substrates requires accurate values of velocity shifts and reflection coefficients caused by the mechanical and electrical loading of the fingers. We describe a simple and reliable method of determining electric reflection and velocity shifts as well as mechanical velocity shifts to first order in h//spl lambda/ for transducers with an anisotropic substrates. We calculate SAW velocities and wavefunctions (displacements and potential) for various substrates with one thin metallic layer. A simple multiplication of the resulting material constants with the appropriate geometrical factor yields the desired SAW parameters. An analogous procedure for the mechanical reflection coefficient is being sought. We present results for many standard SAW substrates and crystal orientations with a metallic overlay, and compare with other first order treatments and some experimental results presently available.","PeriodicalId":268177,"journal":{"name":"1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130530712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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