声表面波在空心圆柱体中的传播特性分析

空心圆柱体管道类的声表面波检测是目前工程检测领域常见的问题.通过势函数和位移假设,建立了声表面波在空心圆柱体内传播的频散方程.数值计算结果表明在空心圆柱体内传播的声表面波与平板中传播的兰姆波存在类似,位移表现为对称和反对称模态.随着频率的增加,低阶模态的相速度逐渐趋于声表面波波速,同时空心圆柱体的壁厚对声表面波相速度的...     

温度效应对声表面波传播的影响

通过引入材料的高阶热膨胀系数和高阶热弹性系数,对半无限大石英晶体内声表面波的传播方程进行了求解,得到了不同温度下的声表面波波速.计算结果表明,温度变化对AT切和ST切石英晶体的声表面波波速有显著影响.最后分析了ST切石英晶体的声表面波的温频特性,结果表明,由温度变化引起的频率漂移很明显.     

静电场对压电薄膜中声表面波传播的影响

该文介绍了声表面波(SAW)在压电薄膜中传播时静电场的影响机理。首先给出了静电场作用下压电薄膜中的初始应力和初始电位移,然后通过求解含有初始应力和初始电位移的压电介质耦合波动方程,得到SAW在静电场影响下的相速度变化和频散曲线,最后仿真分析了ZnO和AlN两种压电薄膜材料中SAW的传播特性。结果表明,SAW的相速度与静电场成正比,与波数成反比。     

声表面波谐振器的时域响应特性研究

由于电磁波的速度比声表面波的速度快得多。叉指换能器在进行电声转换的同时．也降低了信号能量流的速度。在一定时间内蓄积了电磁能量。所以当电磁激励结束后的一定时间内，声表面波器件仍然有瞬态输出，这是声表器件实现无源无线传感的物理基础。该文通过推导声表面波谐振器各部分的冲激响应函数，得到谐振器的冲激响应。据此分析研究声表面波谐振器在各种激励下的响应波形和特征。分析表明声表面波谐振器的瞬态响应完全反映了器件的性能参数。     

S型声表面波器件特性分析

在128°Y切割X传播方向上的L iN bO3基片上设计并研制了S型声表面波器件。它将输入IDT激发的声表面波中心对称分成两路并由各自的输出IDT检测输出。应用P矩阵法分析了其中一输出IDT检测输出的1次时延信号、3次和5次渡越反射信号与输入IDT所加的电信号之间的关系式,并与“一”字型器件的3次渡越反射信号进行对比。结果表明,S型声表面波器件能有效地降低3次和5次渡越反射信号。     

基于耦合模理论的Y型声表面波器件特性分析

声表面波理论是研究高性能声表面波器件的理论基础。耦合模理论因能正确、全面反映声表面波在压电材料上的传播特性得到广泛的重视。应用耦合模理论分析推导自行研制的Y型声表面波器件特性,并编制相应的软件包。应用该软件包计算Y型声表面波器件中心频率处的插入损耗(-12．6dB)与实验结果(约-13dB)相近,为声表面波器件提供一种有效的分析工具。     

应用在移动通信中的声表面波滤波器

应用在移动通信中的声表面波滤波器庄直铭声表面波器件（ＳＡＷＤ）是一种在信号处理、频率控制、频率选择、信息捕获诸方面性能十分优良的器件。７０年代末，电视机中由十几个元件组成的ＬＣ滤波器，逐渐被声表面波滤波器（ＳＡＷＦ）所取代，从而使电路简化，调整方便，...     

Y型声表面波器件特性分析

在1280旋转Y切割X传播方向上的L iN bO3基片上设计并研制了Y型声表面波器件。它将输入IDT激发的声表面波轴对称分成两路并由各自的输出IDT检测输出。应用P矩阵法分析了其中一输出IDT检测输出的一次时延信号、三次渡越反射信号和五次渡越反射信号与输入IDT所加的电信号之间的关系式,并应用网络分析仪测量Y型声表面波器件幅度特性,结果表明,理论分析与实验结果基本相符。     

激光扫描探测声表面波特性

介绍一种新型的探测声表面波传输特性的测量技术.实现了各向异性晶体声表面波衍射场分布的一维扫描显示;二维扫描在电视屏上可对声表面波阵面直接成象,在此基础上求出了声表面波相速以及探测声表面波器件表面缺陷.     

声表面波器件在移动通信中的应用

本文简单介绍了声表面波滤波器的原理、声表面波滤波器在移动通信系统中的应用和应用中应注意的问题，展望了声表面波器件的发展趋势。     

Analysis of propagation in ridge guides for acoustic surface waves

Two models are proposed to describe propagation along an acoustic-surface ridge waveguide, formed by substrate deformation. The higher-order mode spectrum is discussed, and we demonstrate the feasibility of controlling dispersion geometrically.     

Practical surface acoustic wave devices

A tutorial discussion is presented on selected surface acoustic wave (SAW) devices for the use of engineers and electronic systems designers. Currently practical components for use in radar systems, communications systems, and as frequency domain filters are described. Emphasis is placed on nondispersive and dispersive delay lines, devices for generating and detecting various radar waveforms, devices for generating and detecting fixed and programmable biphase and multiphase codes, and broad-band and narrow-band filters. The device possibilities of several new approaches are described, including multistrip couplers, nonlinear convolvers, reflective structures, and overlay films. It is concluded that, while SAW devices have found many applications in large radar systems because of their size, cost effectiveness, and reliability, wide-scale applications, for example as frequency domain filters, will be needed to justify continued research in this field. Wide-scale applications will come as systems engineers realize the potential of these devices and confidently design them into their systems.     

MEMS-IDT声表面波陀螺

声表面波陀螺的概念出现在70年代初期,发展为MEMS-IDT声表面波陀螺仅是最近几年的事情。MEMS-IDT声表面波陀螺仪是一种MEMS微机械振动陀螺,这种陀螺为单层平面结构,采用标准IC工艺就可完成加工,勿需悬浮的振动元件,有很强的抗冲击振动能力,可靠性高,可不用真空封装而保持较高的灵敏度。     

Frequency-selective scanning of acoustic surface wave

An acoustic-surface-wave point source is obtained when an interdigital transducer with concentric curved fingers is used. An array transducer composed of 80 point sources has been tested. The direction of propagation of the surface-wave beam emitted by this transducer depends on the frequency. A transmitting-array transducer and five receiving transducers are deposited on a quartz substrate. Each of these five outputs corresponds to a given frequency and delay prescribed by the positioning. At 12°, scanning was attained for a frequency variation of 7.6 MHz around a central frequency of about 60 MHz, corresponding to a delay variation of 18.2 ?s.     

A high-frequency surface acoustic wave resonator

The results of mathematical modeling of an interdigital converter of surface acoustic waves are presented. An equivalent circuit model is used. It is shown that the choice of the number of electrodes in the converter makes it possible to use it as a miniature high-quality resonator.     

Theoretical and experimental study of superhigh electromechanicalcoupling surface acoustic wave propagation in KNbO3 singlecrystal

The propagation characteristics of surface acoustic waves (SAWs) and piezoelectric leaky surface waves in single crystal KNbO₃ were investigated theoretically and experimentally. The results show that the electromechanical coupling coefficient of the surface wave propagating along the X-axis of the rotated Y-cut plane is very large, K ²=0.53, compared to K² of 0.055 for LiNbO₃      

Wall surface wave effects in WLAN propagation environments

Indoor and outdoor urban environments are a class of open boundary structures capable of supporting surface waves on walls of buildings. The excitation of surface waves on common building materials is investigated and demonstrated to illustrate the implications for wireless local area networks.     

薄膜声表面波器件的制备研究进展

介绍了薄膜声表面波器件的发展历史和特点,以及压电薄膜声表面波器件近年来国际上的研究进展,包括理论研究与实验进展的一些概况,并展望了其今后的发展趋势。     

A surface acoustic wave delay line phase amplifier

Theoretical analysis of surface acoustic wave (SAW) delay line resonators is extended to show the possibility of a novel circuit, which can be used to amplify the phase shift of a fixed frequency signal associated with an electronic circuit.