声表面波无源无线传感器研究

本文阐述了声表面波无源无线传感器的分类、原理和特点,详细介绍了声表面波无源无线传感器的发展历史、成功应用实例和国内外研究现状,分析了该传感器与其它传感器相比的优势和存在的不足之处,展望了研究的学术意义和潜在的应用前景.     

无线无源声表面波气压传感器

阐述了声表面波气压传感器的设计原理、结构及相应的遥测系统和数据采样处理系统。应用正交相位检测法,将几纳秒的时间差测量转化成较大的相位测量。采用回波幅值触发采样,有效提高采样及数据处理效率。设计的SAW气压传感器理论灵敏度可达0.7kPa,测量范围在为10～350kPa。     

声表面波无源无线传感系统

介绍了一种新型的无源、无线声表面波传感系统。传感器单元无电源供电，传感的能量来自外界的无线电磁波。传感器单元间，输入和输出均采用非接触的无线方式，无需电线连接。在声表面波传感器中，特殊叉指换能器构造了无源无线编码器和解码器，它能对众多传感器单元编码。该传感器可广泛应用于各种智能结构系统和工程应用中。     

基于声表面波延迟线和谐振器的无源无线阵列传感器

本文介绍了延迟线型无源无线声表面波传感器的结构、传感器系统的组成、工作原理和传输特性.在分析延迟线型无源无线声表面波传感器缺点的基础上,提出了一种全新的谐振延迟型无源无线声表面波传感器的模型,并用延迟线和谐振器构造了这种传感器.它既有谐振型传感器传感距离远的优点,又有延迟线型传感器容易编码的优势.本文还分析了该传感器的信号响应特性和传感器系统的构造.     

声表面波谐振器无源无线传感虚拟仪器系统

分析了在通用硬件平台上结合软件设计的声表面波谐振器无源无线传感虚拟仪器系统。该系统通过设计虚拟仪器实现部分硬件功能,控制闭环系统实现自动检测,并采用数字信号处理方法提高检测系统的精度,从而避免了通常的复杂硬件系统,降低硬件成本,并使检测更灵活。本文介绍了设计原理和系统构成,并对系统的误差进行了分析。实验表明:该仪器系统能够达到5m的无线检测距离。     

无源声表面波谐振器的无线温度传感系统

介绍了一种基于声表面波谐振器的无源无线温度传感系统。作为传感器的谐振器受到正弦脉冲串的无线激励。因激励信号的中心频率不同于谐振器的谐振频率，所以回波信号是一调幅信号，其包络的主频就是谐振器的谐振频率和激励信号中心频率的差频。给出了传感系统的电路设计以及信号处理方法。实验数据和器件的温度系数吻合。     

无线无源声表面波传感器研究进展

声表面波（SAW）传感器是一种无线无源传感器,在无源传感、适应恶劣环境等许多方面具有普通传感器不能实现的优点.阐述了声表面波器件的原理和结构特点,并对射频信号收发、信息处理等关键技术进行详细论述,综述了近些年国内外的相关研究现状,并进行了总结与展望.     

小型化多频带微带天线的设计

第三代移动通信对天线的小型化和多频带提出了越来越高的要求,提出了一种双U型槽和弧形边联合加载的平面倒L天线,采用微带馈电;从蜂窝移动通信、全球定位系统和蓝牙通讯对天线的要求出发,设计了两个四频天线:一个覆盖GSM/DCS/PCS/ISM频段,另一个覆盖GSM/GPS/PCS/ISM频段;应用ANSOFT公司的HFSS10.0三维仿真软件,对天线进行设计和优化,最终得到了两个基本符合频段带宽及方向图要求的四频天线,这对微带天线的小型化和多频带技术具有一定的指导意义。     

应用于WSN的小型化微带天线的研究

基于目前对WSN(无线传感器网络)的需求,本文设计了一种工作在2.4GHz的小型化的矩形开槽微带贴片天线,由于采用了曲流技术,该天线比一般微带天线要小,当工作在2.4GHz时,其导波波长为70mm,天线尺寸为29mm×29mm,长宽均为导波波长的0.4倍。仿真与测试结果表明,实验结果与仿真结果基本吻合。天线的-10dB带宽为24MHz(2.38GHz-2.404GHz),天线的辐射特性较好,在-10dB带宽内,辐射增益均大于0dBi,而且在中心频率2.4GHz处达到最大值6dBi。     

一种基于超高频RFID的无线无源压力传感器

电力设备在长期运行中,受环境影响,可能会发生失压、形变现象。针对这种现象,设计了一种基于UHF RFID的无线无源压力传感器,能够在不接触电力设备的情况下获得设备的表面压力信息。基于UHF RFID的压力传感器标签主要由阻抗自适应RFID芯片、UHF频段RFID偶极子天线、金属极板和支撑弹簧构成。电力设备的形变会导致安装在设备上的金属极板与偶极子天线的相对位置变化,导致RFID天线的阻抗变化,RFID芯片内部会通过自动调节输入阻抗电容以匹配RFID天线阻抗的变换。通过检测RFID芯片内部匹配阻抗的电容值,可以推出电力设备的形变情况,形成一一对应的关系,从而实现无线无源压力传感功能。     

Miniaturization and bandwidth enhancement of a cavity backed circular microstrip patch antenna

The resonant frequency of a circular patch antenna with and without circular cavity is measured. The patch miniaturization in the presence of the cavity is proved. Different methods of reducing resonant frequencies and broadening bandwidth without significantly reducing antenna gain are presented. Capacitively loaded patch and slits on the patch stimulate the patch at lower frequencies and multiple resonances, thus help miniaturization. Finally ferrite loading on the feed probe further increases the bandwidth without significantly reducing the antenna gain. The method is much more improved than that for a resistive loaded patch and a deformed patch. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Harmonics blocking in the inset fed microstrip patch antenna using cascaded defected microstrip structure

In this article a cascaded defected microstrip structures (CDMS) is proposed as the feed line of an inset patch microstrip antenna. Using this feed line, the effective radiation is improved; the higher order harmonics are completely suppressed, the size of antenna is about 10% reduced and also the front‐to‐back ratio parameter is greatly improved. In comparison to a conventional microstrip patch antenna without the CDMS, the radiated power of the CDMS patch antenna at harmonic frequencies even up to the 4th harmonic has been drastically decreased. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

时域加窗技术改进无源无线SAW传感器测试研究

无源无线声表面波(SAW)传感器能工作在十分恶劣的环境中监控温度、应变、扭矩等因素的变化.利用无线测试传感器的群时延特性能方便地获得SAW传感器的谐振频率.但在一些复杂的环境中无线测试时会遇到环境反射的问题,此时测试的群时延曲线会产生畸变,不利于提取SAW传感器的谐振频率.利用测试群时延特性的方法搭建了测试系统,对测试结果使用了时域加窗技术.结果表明:时域加窗技术能够有效抑制环境反射对群时延的影响,这对于提高无源无线SAW传感器实际应用中的信噪比具有重要的意义.     

High gain microstrip antenna design for broadband wireless applications

This article presents a new broadband microstrip antenna for personal communications systems (PCS) applications. Using multilayer substrate structure with aperture‐coupled feed, a rectangular microstrip patch antenna operating at 1.9‐GHz band is designed and experimentally validated. This antenna configuration uses a quarter‐wave transformer to enhance the matching between the feed transmission line and the antenna patch. To demonstrate the design procedure, a first experimental broadband microstrip antenna prototype is designed and implemented. To analyse its performance, measurements are carried out and good performances are achieved. However, this prototype has a low front‐to‐back ratio. To overcome this drawback, an optimization process is proposed, and a second prototype is designed and successfully realized. To examine the effect of the optimization, experimental investigations are carried out on the second prototype. Very good agreement is obtained between numerical and measured results. Experimental results indicate that the proposed antenna achieves a bandwidth of 21%, a gain of 9.5 dB, and a front‐to‐back ratio of 20 dB, which are very sufficient for broadband wireless applications. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13, 511–517, 2003.     

Broadband gap‐coupled half‐hexagonal microstrip antenna fed by microstrip‐line resonator

Half‐hexagonal microstrip antenna (H‐HMSA) is a compact version of HMSA, as it resonates at the same fundamental mode frequency. In this article, a compact configuration of a single layer, broadband gap‐coupled H‐HMSA has been proposed. Gap‐coupled H‐HMSA is fed indirectly by a λ/2 microstrip‐line resonator. Broad bandwidth (BW) is achieved with an effective use of resonance introduced by λ/2 resonator and gap‐coupled half‐hexagonal radiating patches. A peak gain of 7.07 dBi and measured BW (S₁₁ ≤ ?10 dB) of 11.5% at the center frequency of 5.2 GHz have been achieved, which occupies a small volume of 0.023 λ₀³ including the ground plane. The radiation patterns remain in the broadside direction throughout the return loss BW. Simulated results of the proposed antenna configuration are experimentally validated with good agreement.     

Multisegment microstrip patch antenna with Y‐shaped feed

A new antenna structure comprising of multiple radiating microstrip patches, representing a figure of digit eight, proximity fed by a microstrip line is proposed. On a double‐layered substrate of FR4, this antenna achieves multiband functionality in the range of 3.81–12.42 GHz, which covers IEEE 802.11a standards and is suggestive of reconfigurability in frequency and pattern. Details of the antenna design, measured and simulation results are presented. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.     

High isolation dual‐frequency patch antenna integrated with cascade defected microstrip structure

This article presents a high‐isolation dual‐frequency rectangular patch antenna utilizing microstrip feed line integrated with a cascade defected microstrip structure (CDMS). Two types of CDMS are added, T‐shaped CDMS and Dumbbell‐T‐shaped CDMS. Simulation results show using these structures improve isolation up to 70 dB and reduce harmonic signals from transmitter. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

本质安全型无线压力传感器天线设计

提出了一种煤矿井下本质安全型无线压力传感器天线结构的设计方案,研究了金属外壳一侧开口时其参数及天线位置对天线增益的影响。仿真与实测结果表明,天线增益随金属外壳的开口长度和宽度的增大而增加,且增加幅度逐渐减小;天线增益随天线距开口的距离减少而增加;开口侧的金属外壳厚度每减少1mm,天线增益增加约2dB;金属外壳空间高度毫米级变化引起的天线增益变化基本可以忽略;当金属外壳的开口长度和宽度分别为天线波长的1/4与1/8,厚度为2mm,空间高度为41mm,天线位置距开口为1.4mm时,天线辐射增益达到最佳,天线的传播距离约为14m。     

一种无源无线SAW压力传感器结构设计

根据无源无线SAW压力传感器的敏感特点,提出了一种具有较高灵敏度的压力传感器结构设计.传感器的受力敏感部分采用简支梁结构,通过分析找到梁的最大应变点,在梁的上下两侧最大应变区域中心对称分布了两个相同的单端口SAW谐振器.由两个SAW谐振器组成差动式测量结构,具有较高的灵敏度,并减少了温度对测量结果的影响,对迟滞效应带来的误差有一定的补偿作用.