Pub Date : 1997-10-05DOI: 10.1109/ULTSYM.1997.663066
S. Hongo, I. Naliamura, N. Hosokawa
A proximity sensor utilizing an evanescent acoustic field formed by flexural plate waves is proposed. When an object comes into the evanescent field, the acoustic radiation admittance of the bending vibrator may change. Hence, the proximity sensing can be achieved by measuring the electrical admittance of the piezoelectric flexural vibrator. To confirm the characteristics of the proximity sensor, some experiments were carried out using a flexural vibrator consisting of a 140/spl deg/ rotated Y-cut LiNbO/sub 3/ plate with a polarization-inverted layer. When an object was approached to the major surface of the vibrator, the admittance at a resonance of the bending vibrator decreased drastically according as the distance d between the object and the vibrator became short. On the other hand, when the object was approached to the tip of the vibrator, the Q-factor decreased in the range d>0.2 mm but increased again unexpectedly in the range d<0.2 mm.
{"title":"Proximity sensors utilizing an evanescent acoustic field formed by flexural plate waves","authors":"S. Hongo, I. Naliamura, N. Hosokawa","doi":"10.1109/ULTSYM.1997.663066","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.663066","url":null,"abstract":"A proximity sensor utilizing an evanescent acoustic field formed by flexural plate waves is proposed. When an object comes into the evanescent field, the acoustic radiation admittance of the bending vibrator may change. Hence, the proximity sensing can be achieved by measuring the electrical admittance of the piezoelectric flexural vibrator. To confirm the characteristics of the proximity sensor, some experiments were carried out using a flexural vibrator consisting of a 140/spl deg/ rotated Y-cut LiNbO/sub 3/ plate with a polarization-inverted layer. When an object was approached to the major surface of the vibrator, the admittance at a resonance of the bending vibrator decreased drastically according as the distance d between the object and the vibrator became short. On the other hand, when the object was approached to the tip of the vibrator, the Q-factor decreased in the range d>0.2 mm but increased again unexpectedly in the range d<0.2 mm.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"4 1","pages":"475-478 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91137596","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.661772
P. Laugier, P. Giat, C. Chappard, C. Roux, G. Berger
Current commercial ultrasound "bone densitometers" process only the through-transmitted signals while failing to extract additional information contained in the scattered signals. This work was conducted to investigate the clinical interest of a backscatter ultrasound technique for bone characterization in 24 healthy premenopausal (group N), 24 postmenopausal (group PM), and 13 osteoporotic patients with fractures (group O). Pulse-echo measurements of the backscatter power were performed at the calcaneus (heel bone) using an ultrasound bone imaging scanner. The pulse-echo waveforms backscattered by the internal trabecular micro-architecture were recorded to compute the integrated backscatter coefficient (BUB, dB) in the frequency range 200-600 kHz. BUB was compared to the slope of the frequency-dependent attenuation (BUA, dB/MHz) derived from signals transmitted through the bone and to bone mineral density. Measurements were averaged in an operator-independent automatic ROI. The short-term reproducibility was 1.4%, and 3.5% for BUA, and BUB respectively. Femoral bone mass density (BMD) was measured in all subjects and calcaneal BMD was measured in a subset of 30 patients. The correlation between ultrasound and calcaneal BMD was moderate for BUB (r=0.55, p<10/sup -3/) and strong for BUA (r=0.82, p<10/sup -4/). Significant differences were found in ultrasound parameters and BMD between fracture and non-fracture groups. There was a significant difference in BMD and ultrasound parameters between young normal controls and healthy post-menopausal women. In summary, reflection ultrasound appears to be promising in osteoporosis and larger studies are clearly warranted.
{"title":"Clinical assessment of the backscatter coefficient in osteoporosis","authors":"P. Laugier, P. Giat, C. Chappard, C. Roux, G. Berger","doi":"10.1109/ULTSYM.1997.661772","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.661772","url":null,"abstract":"Current commercial ultrasound \"bone densitometers\" process only the through-transmitted signals while failing to extract additional information contained in the scattered signals. This work was conducted to investigate the clinical interest of a backscatter ultrasound technique for bone characterization in 24 healthy premenopausal (group N), 24 postmenopausal (group PM), and 13 osteoporotic patients with fractures (group O). Pulse-echo measurements of the backscatter power were performed at the calcaneus (heel bone) using an ultrasound bone imaging scanner. The pulse-echo waveforms backscattered by the internal trabecular micro-architecture were recorded to compute the integrated backscatter coefficient (BUB, dB) in the frequency range 200-600 kHz. BUB was compared to the slope of the frequency-dependent attenuation (BUA, dB/MHz) derived from signals transmitted through the bone and to bone mineral density. Measurements were averaged in an operator-independent automatic ROI. The short-term reproducibility was 1.4%, and 3.5% for BUA, and BUB respectively. Femoral bone mass density (BMD) was measured in all subjects and calcaneal BMD was measured in a subset of 30 patients. The correlation between ultrasound and calcaneal BMD was moderate for BUB (r=0.55, p<10/sup -3/) and strong for BUA (r=0.82, p<10/sup -4/). Significant differences were found in ultrasound parameters and BMD between fracture and non-fracture groups. There was a significant difference in BMD and ultrasound parameters between young normal controls and healthy post-menopausal women. In summary, reflection ultrasound appears to be promising in osteoporosis and larger studies are clearly warranted.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"33 1","pages":"1101-1104 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75096096","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.663340
M. Lukacs, M. Sayer, S. Foster
PZT coatings have been produced in the thickness range of 5-200 microns using a composite sol gel process (M. Lukacs et al., 1996). The application of this process in the fabrication of high frequency transducers suitable for ultrasound biomicroscopy (UBM) has been investigated. Curved single element transducers have been produced in a range of 70-165 MHz with -6dB bandwidths as high as 52% and minimum insertion losses ranging from -47 to -58 dB. Laser micromachining techniques for patterning linear array structures to operate at similar frequencies have been developed. Trenches <10 /spl mu/m wide with a 50% taper through 20 /spl mu/m of ceramic have been achieved with a pulsed frequency doubled Nd:YAG laser. Trenches 5 /spl mu/m wide with straight walls have been achieved using a pulsed KrF excimer laser.
{"title":"Single element and linear array PZT ultrasound biomicroscopy transducers","authors":"M. Lukacs, M. Sayer, S. Foster","doi":"10.1109/ULTSYM.1997.663340","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.663340","url":null,"abstract":"PZT coatings have been produced in the thickness range of 5-200 microns using a composite sol gel process (M. Lukacs et al., 1996). The application of this process in the fabrication of high frequency transducers suitable for ultrasound biomicroscopy (UBM) has been investigated. Curved single element transducers have been produced in a range of 70-165 MHz with -6dB bandwidths as high as 52% and minimum insertion losses ranging from -47 to -58 dB. Laser micromachining techniques for patterning linear array structures to operate at similar frequencies have been developed. Trenches <10 /spl mu/m wide with a 50% taper through 20 /spl mu/m of ceramic have been achieved with a pulsed frequency doubled Nd:YAG laser. Trenches 5 /spl mu/m wide with straight walls have been achieved using a pulsed KrF excimer laser.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"35 1","pages":"1709-1712 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76653769","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.663095
P. Fomitchov, A. Kromine, S. Krishnaswamy, J. Achenbach
Knowledge of the spatial and temporal parameters of ultrasonic beams, as well as details of interaction of such beams with small defects is necessary for effective application of ultrasonic techniques to nondestructive evaluation (NDE). The work presented here employs a fiber-optic Sagnac interferometer to characterize acoustical fields generated by conventional piezoelectric transducers (PZT) and a laser ultrasonic source, and the scattering of such ultrasonic fields by flaws. The high spatial resolution of this interferometer and its ability to provide absolute ultrasonic displacements make this device very suitable for: (i) profiling and calibration of ultrasonic beams generated by PZT transducers or laser sources, and (ii) precision measurement of ultrasonic fields scattered by flaws.
{"title":"Application of a Sagnac interferometer for the characterization of scattered ultrasonic fields","authors":"P. Fomitchov, A. Kromine, S. Krishnaswamy, J. Achenbach","doi":"10.1109/ULTSYM.1997.663095","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.663095","url":null,"abstract":"Knowledge of the spatial and temporal parameters of ultrasonic beams, as well as details of interaction of such beams with small defects is necessary for effective application of ultrasonic techniques to nondestructive evaluation (NDE). The work presented here employs a fiber-optic Sagnac interferometer to characterize acoustical fields generated by conventional piezoelectric transducers (PZT) and a laser ultrasonic source, and the scattering of such ultrasonic fields by flaws. The high spatial resolution of this interferometer and its ability to provide absolute ultrasonic displacements make this device very suitable for: (i) profiling and calibration of ultrasonic beams generated by PZT transducers or laser sources, and (ii) precision measurement of ultrasonic fields scattered by flaws.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"15 1","pages":"609-612 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74347307","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.663014
E. Henry, S. Ballandras, E. Bigler, G. Marianneau, G. Martin, S. Camou
Most Surface Acoustic Wave (SAW) devices exhibit a very small sensitivity to thermal effects. However, even on instrinsically compensated crystal cuts, the deposition of metal strips at the surface (transducers or reflectors) induces important changes in the thermoelastic properties of the device. A theoretical approach based on the Sinha-Tiersten perturbation method is proposed to model the influence of metallization on SAW properties on (ST,X) quartz, namely the temperature stability of the phase velocity of Rayleigh waves. Since this perturbation method only gives access to the first order Temperature Coefficient of Frequency (TCF), it is combined with a conventional calculation of the second order TCF to predict the evolution of the turnover temperature. The proposed calculation also requires temperature derivatives of the elastic constants of the metal which can be calculated for different materials. More classical approaches are also considered based on the calculation of surface permittivity using thermally varied elastic constants. Finally, theoretical results are compared to experimental data measured on SAW devices on (ST,X) quartz using Aluminium, Gold or Chromium gratings.
{"title":"Influence of metallization on temperature stability of SAW devices","authors":"E. Henry, S. Ballandras, E. Bigler, G. Marianneau, G. Martin, S. Camou","doi":"10.1109/ULTSYM.1997.663014","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.663014","url":null,"abstract":"Most Surface Acoustic Wave (SAW) devices exhibit a very small sensitivity to thermal effects. However, even on instrinsically compensated crystal cuts, the deposition of metal strips at the surface (transducers or reflectors) induces important changes in the thermoelastic properties of the device. A theoretical approach based on the Sinha-Tiersten perturbation method is proposed to model the influence of metallization on SAW properties on (ST,X) quartz, namely the temperature stability of the phase velocity of Rayleigh waves. Since this perturbation method only gives access to the first order Temperature Coefficient of Frequency (TCF), it is combined with a conventional calculation of the second order TCF to predict the evolution of the turnover temperature. The proposed calculation also requires temperature derivatives of the elastic constants of the metal which can be calculated for different materials. More classical approaches are also considered based on the calculation of surface permittivity using thermally varied elastic constants. Finally, theoretical results are compared to experimental data measured on SAW devices on (ST,X) quartz using Aluminium, Gold or Chromium gratings.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"286 1","pages":"221-225 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77149309","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.663083
Q.M. Zhang, X. Geng
A model is derived for the analysis of the dynamic behavior of 1-3 piezocomposites. Based on this model, the effective parameters and their dependence on the aspect ratio of the unit cell of a 1-3 composite, can be evaluated. From the model we show that the mechanical quality factor of a composite can be lower than that of both the ceramic and polymer. The predictions are compared with experimental results and the agreement between the two is quite satisfactory.
{"title":"Acoustic and electromechanical behavior of 1-3 piezocomposites for ultrasonic transducer applications","authors":"Q.M. Zhang, X. Geng","doi":"10.1109/ULTSYM.1997.663083","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.663083","url":null,"abstract":"A model is derived for the analysis of the dynamic behavior of 1-3 piezocomposites. Based on this model, the effective parameters and their dependence on the aspect ratio of the unit cell of a 1-3 composite, can be evaluated. From the model we show that the mechanical quality factor of a composite can be lower than that of both the ceramic and polymer. The predictions are compared with experimental results and the agreement between the two is quite satisfactory.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"20 1","pages":"557-560 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76044228","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.661859
L. M. Hinkelman, T. Mast, M. J. Orr, R. Waag
Wavefront propagation through the abdominal wall was investigated by measurements employing full-thickness specimens and their individual fat and muscle layers. These measurements confirm that both fat and muscle produce significant wavefront distortion and focus degradation. However, the spatial characteristics of the distortion produced by fat and muscle differ, and the total distortion produced by the abdominal wall is not the arithmetic sum of that produced by the individual layers. The interface between the muscle and subcutaneous fat layers, which consists of a thin layer of connective tissue, was found to be smooth or slightly curved. Distortion produced by different tissues was further characterized by simulations using a finite-difference time-domain implementation of the linearized wave propagation equations for a lossless inhomogeneous fluid. Scanned images of six human abdominal wall cross sections provided the data for the propagation media in the simulation. The images were mapped into regions of fat, muscle, and connective tissue, each of which was assigned a uniform sound speed and density obtained from literature values. The computed wavefronts contained arrival time, energy level, and wave shape distortion similar to that in measurements. Visualization of wave propagation within the tissue cross sections suggests that most arrival time distortion is produced by acoustic path length differences while amplitude and waveform variations are the result of scattering from inhomogeneities. Many arrival time fluctuation and energy level fluctuation features could be traced to specific anatomical structures. These results indicate that wavefront distortion, apart from bulk attenuation effects, is primarily caused by tissue structures and inhomogeneities rather than refraction at layer interfaces.
{"title":"Effects of abdominal wall morphology on ultrasonic pulse distortion","authors":"L. M. Hinkelman, T. Mast, M. J. Orr, R. Waag","doi":"10.1109/ULTSYM.1997.661859","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.661859","url":null,"abstract":"Wavefront propagation through the abdominal wall was investigated by measurements employing full-thickness specimens and their individual fat and muscle layers. These measurements confirm that both fat and muscle produce significant wavefront distortion and focus degradation. However, the spatial characteristics of the distortion produced by fat and muscle differ, and the total distortion produced by the abdominal wall is not the arithmetic sum of that produced by the individual layers. The interface between the muscle and subcutaneous fat layers, which consists of a thin layer of connective tissue, was found to be smooth or slightly curved. Distortion produced by different tissues was further characterized by simulations using a finite-difference time-domain implementation of the linearized wave propagation equations for a lossless inhomogeneous fluid. Scanned images of six human abdominal wall cross sections provided the data for the propagation media in the simulation. The images were mapped into regions of fat, muscle, and connective tissue, each of which was assigned a uniform sound speed and density obtained from literature values. The computed wavefronts contained arrival time, energy level, and wave shape distortion similar to that in measurements. Visualization of wave propagation within the tissue cross sections suggests that most arrival time distortion is produced by acoustic path length differences while amplitude and waveform variations are the result of scattering from inhomogeneities. Many arrival time fluctuation and energy level fluctuation features could be traced to specific anatomical structures. These results indicate that wavefront distortion, apart from bulk attenuation effects, is primarily caused by tissue structures and inhomogeneities rather than refraction at layer interfaces.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"113 1","pages":"1493-1496 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79864138","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.661765
S. Bridal, J. Toussaint, J. Raynaud, P. Fornés, A. Leroy-Willig, G. Berger
This study compares quantitative characterization of plaque by high resolution estimates of ultrasonic attenuation, ultrasonic backscatter and magnetic resonance transverse relaxation time. A total of 54 regions of in vitro human arteries were studied. Backscattered radio frequency signals were acquired with a 50 MHz backscatter acoustic microscope. Ultrasonic parametric images were constructed from the integrated (30 to 50 MHz) backscatter and attenuation obtained using FFT methods with diffraction correction and a multinarrow-band attenuation algorithm. Magnetic resonance images were constructed from estimates of the transverse relaxation time determined by an 8 echo-monoslice sequence at 3 Tesla. Histological segments obtained at each measurement site were used to identify tissue composition. Results suggest that combined ultrasound and magnetic resonance techniques may offer complementary information for plaque characterization.
{"title":"Multi-parametric imaging of atherosclerotic plaque by 50 MHz ultrasound and 3 Tesla magnetic resonance","authors":"S. Bridal, J. Toussaint, J. Raynaud, P. Fornés, A. Leroy-Willig, G. Berger","doi":"10.1109/ULTSYM.1997.661765","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.661765","url":null,"abstract":"This study compares quantitative characterization of plaque by high resolution estimates of ultrasonic attenuation, ultrasonic backscatter and magnetic resonance transverse relaxation time. A total of 54 regions of in vitro human arteries were studied. Backscattered radio frequency signals were acquired with a 50 MHz backscatter acoustic microscope. Ultrasonic parametric images were constructed from the integrated (30 to 50 MHz) backscatter and attenuation obtained using FFT methods with diffraction correction and a multinarrow-band attenuation algorithm. Magnetic resonance images were constructed from estimates of the transverse relaxation time determined by an 8 echo-monoslice sequence at 3 Tesla. Histological segments obtained at each measurement site were used to identify tissue composition. Results suggest that combined ultrasound and magnetic resonance techniques may offer complementary information for plaque characterization.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"2 1","pages":"1071-1074 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80359167","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.662992
S. Balashov, C. M. Cabreira, C. Finardi
Low loss filters based on Single Phase Unidirectional Transducers (SPUDT) could be characterized as a separate class of Surface Acoustic Wave (SAW) filters because they overcome the main SAW filters limitation-6 dB bidirectional insertion loss. For the substrate with the high value of electroacoustic coupling coefficient k/sup 2/ the main effect used to obtain unidirectionality is electrical regeneration which could be treated directly by the Green's Function Model (GFM). The GFM being applicable to an interdigital transducer (IDT) with arbitrary topology is difficult to be applied to the IDT with large number of periods because computation time increases in power law with growth of the IDT length reaching very quickly unacceptable values. In this paper we present the method for calculation of arbitrary SAW filter parameters based on the GFM. Symmetry consideration being used for presentation of the central region of the long IDT, computation time decreases dramatically. At the same time edge effects of the IDT are correctly taken into account. The method developed works both for high and low k/sup 2/ value substrates. Results of calculation of SPUDT characteristics with the help of method proposed are presented.
基于单相单向换能器(SPUDT)的低损耗滤波器可以作为表面声波(SAW)滤波器的一个独立类别，因为它克服了主要表面声波滤波器的限制-6 dB双向插入损耗。对于高电声耦合系数k/sup 2/的基板，获得单向性的主要作用是电再生，可直接用格林函数模型(Green’s Function Model, GFM)进行处理。GFM适用于任意拓扑的数字间换能器(IDT)，但由于计算时间随着IDT长度的增长呈幂律增长，很快达到不可接受的值，因此很难应用于周期较大的IDT。本文提出了一种基于GFM的任意声表面波滤波器参数的计算方法。利用对称的考虑来表示长IDT的中心区域，大大减少了计算时间。同时，正确地考虑了IDT的边缘效应。所开发的方法适用于高/低k/sup / value衬底。给出了利用该方法计算SPUDT特性的结果。
{"title":"Modified Green's function approach to analysis of long SAW transducers","authors":"S. Balashov, C. M. Cabreira, C. Finardi","doi":"10.1109/ULTSYM.1997.662992","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.662992","url":null,"abstract":"Low loss filters based on Single Phase Unidirectional Transducers (SPUDT) could be characterized as a separate class of Surface Acoustic Wave (SAW) filters because they overcome the main SAW filters limitation-6 dB bidirectional insertion loss. For the substrate with the high value of electroacoustic coupling coefficient k/sup 2/ the main effect used to obtain unidirectionality is electrical regeneration which could be treated directly by the Green's Function Model (GFM). The GFM being applicable to an interdigital transducer (IDT) with arbitrary topology is difficult to be applied to the IDT with large number of periods because computation time increases in power law with growth of the IDT length reaching very quickly unacceptable values. In this paper we present the method for calculation of arbitrary SAW filter parameters based on the GFM. Symmetry consideration being used for presentation of the central region of the long IDT, computation time decreases dramatically. At the same time edge effects of the IDT are correctly taken into account. The method developed works both for high and low k/sup 2/ value substrates. Results of calculation of SPUDT characteristics with the help of method proposed are presented.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"201 1","pages":"123-126 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80144256","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 : 1997-10-05DOI: 10.1109/ULTSYM.1997.663002
T. Shiba, Y. Fujita, N. Kamogawa, N. Hosaka, S. Ogawa, K. Oda, M. Hikita
A fully comprehensive electrical admittance matrix composition technique including the effects of residual electrical elements (capacitance, inductance and resistance) will be reported corresponding the various kind of the devices. An automatic design technique based on the optimization method is applied using the above composition routine. The automatic design procedure determines the parameters for SAW Filter elements and the external circuit element. It is possible that the procedure perform using measured admittance matrix elements. In order to verify the technique dual band filters and duplexers for digital mobile terminals were designed using the above procedure. The performance of these devices was found to be in good agreement with the design predictions.
{"title":"Automatic design procedure using circuit composition technique for SAW devices","authors":"T. Shiba, Y. Fujita, N. Kamogawa, N. Hosaka, S. Ogawa, K. Oda, M. Hikita","doi":"10.1109/ULTSYM.1997.663002","DOIUrl":"https://doi.org/10.1109/ULTSYM.1997.663002","url":null,"abstract":"A fully comprehensive electrical admittance matrix composition technique including the effects of residual electrical elements (capacitance, inductance and resistance) will be reported corresponding the various kind of the devices. An automatic design technique based on the optimization method is applied using the above composition routine. The automatic design procedure determines the parameters for SAW Filter elements and the external circuit element. It is possible that the procedure perform using measured admittance matrix elements. In order to verify the technique dual band filters and duplexers for digital mobile terminals were designed using the above procedure. The performance of these devices was found to be in good agreement with the design predictions.","PeriodicalId":6369,"journal":{"name":"1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118)","volume":"66 1","pages":"165-170 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1997-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82847792","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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