压电陶瓷三叠片复合换能器弯曲振动特性研究

采用瑞利法对固定边界条件下,三叠片圆盘弯振换能器进行理论研究,推导其谐振频率及有效机电耦合系数,通过数值计算分析换能器谐振频率及有效机电耦合系数随换能器各尺寸参数的变化规律,并与有限元模拟结果比较,结果表明,换能器结构参数对谐振频率和有效机电耦合系数有很大影响,有效机电耦合系数在其他尺寸已定的情况下随着金属片厚度、陶瓷片厚度和半径变化时,都有一个最大值,这为三叠片弯曲振动换能器的设计和进一步广泛应用提供理论支持。     

具有电或磁耦合关系谐振电路的谐振频率

采用本征值理论分析与电路仿真两种独立的方法,定量计算了具有电耦合或磁耦合关系谐振电路的谐振频率随耦合电容或耦合系数大小的变化关系,两种耦合电路的谐振频率表现出不同的变化规律。这种耦合谐振电路的分析为实际电路设计过程中利用耦合类型及耦合强度对谐振频率进行调谐开辟了新的途径,扩展了现有教学中无耦合谐振电路的教学内容。     

谐振式微光学陀螺系统设计

集成化、微型化是谐振式光学陀螺的发展趋势之一.通过分析在一定激光器线宽情况下,谐振式微光学陀螺(R-MOG)系统极限灵敏度和环形谐振腔光路中各主要参数之间的关系,得到环形谐振腔耦合系数与环形谐振腔损耗参数间的关系.设计优化R-MOG系统的主要光学参数,使得系统的极限灵敏度达到最高.并且对实际设计的集成微光学环形谐振腔组成的R-MOG系统进行模拟转动的开环响应测试.为R-MOG系统的构建提供了理论及实验基础.     

一种改进型1-3-2压电复合材料的研究

高质量的压电换能器需要具备较高的机电耦合系数和灵敏度。该文在传统型1-3-2压电复合材料的基础上提出了一种改进型1-3-2压电材料,提高了压电换能器的机电耦合系数和换能器的接收灵敏度。通过有限元仿真分析了不同间距对改进型1-3-2压电材料敏感元件的谐振频率、反谐振频率及机电耦合系数的影响,并与传统1-3-2型压电复合材料进行了对比。结果表明,与传统型1-3-2压电复合材料相比,在相同间距条件下,改进型压电材料的机电耦合系数约大0.03。制做的3种不同间距改进型压电材料表明,间距为1 mm的改进型压电材料的机电耦合系数较大,约为0.68。     

高次泛音比法测定厚度振动机电耦合系数

压电振子低频振动模式的高次泛音易与厚度振动模式的基频相耦合,导致厚度振动的基音串联谐振频率不能精确测量(或无法测量),造成传统泛音比法测定压电振子的机电耦合系数的精度和一致性变差或无法进行测定。为了克服传统泛音比法的这一弊端,提出了测定压电振子厚度振动机电耦合系数的高次泛音比法。此法通过测定3次和3次以上的高次串联谐振频率,用高次泛音比来测定压电振子厚度振动机电耦合系数。实验表明,与传统泛音比法相比,高次泛音比法具有精确度高和一致性好的明显优势。为了便于高次泛音比法的应用,提供了高次泛音比和机电耦合系数的对应表。     

Cymbal换能器试验研究

研究了Cymbal换能器的形状参数对位移放大作用的影响,以及Cymbal的谐振特性、迟滞系数、响应时间、有效机电耦合系数。通过优化端帽形状参数和制作工艺改善了Cymbal的位移放大作用和频率谐振等特性。其直流电场下位移放大作用是PZT-5的38倍,交流电场下达60倍。等效压电系数达22550 pm/V,谐振频率从28.54~58.53 kHz,响应时间为17~35μs。     

耦合振动夹心式换能器的振动模态研究

基于有限元法,研究了横向尺寸对换能器谐振频率及其耦合振动特性的影响.研究表明,换能器的纵向谐振频率并非随横向尺寸的增大连续降低,而是呈分段降低的趋势,在段与段之间出现了不连续的跃变;随着横向尺寸的增加,耦合振动随之加强,除纵向谐振模态外,有越来越多的径向及耦合谐振模态被激发,换能器的频谱变得更丰富.据此,通过选择合适的纵向和横向尺寸,为设计多频换能器提供思路.     

谐振式能量传输系统频率分裂特性研究

基于磁耦合谐振式的无线供电系统可在中等传输距离内实现高效能量传输,因而成为当前科学与工程技术领域研究的热点.主要研究了磁耦合谐振式无线供电系统在传输过程中有可能存在的频率分裂现象.通过在FEKO中对磁耦合谐振式无线供电系统进行建模分析,验证了现象的存在,并指出前人解决频率分裂方法的局限性.提出一种可行的方法去消除频率分裂现象对系统传输的影响,为后续磁耦合谐振式无线能量传输系统的设计提供参考.     

微波介质陶瓷材料介电性能间的制约关系

微波介质陶瓷材料的三个主要参数相对介电常数εr、品质因数Q和谐振频率温度系数之间存在一定的关系。采用一维双原子线性振动模型,分析了微波介质陶瓷材料的εr、Q影响因素和它们之间的相互制约关系;采用Clausius-Mosotti方程,分析了谐振频率温度系数的影响因素以及它和εr之间的相互制约关系。讨论了提高高介微波介质陶瓷材料性能的途径,发现采用同电价质量较轻的离子取代,在基本不影响介电常数的情况下具有提高材料的Q·f值的可能性。     

无隔模带磁控管谐振系统的理论分析与仿真

为了提高磁控管稳定性,需要研究各耦合因素对磁控管谐振频率及模式分隔度的影响。该文采用等效电路的方法,给出了无隔模带磁控管在电容、电感耦合下的谐振频率及模式分隔度的表达式,并分析谐振频率随模数的变化趋势及电感、电容耦合强弱对模式分隔度的影响。采用CST-MWS软件对不同阴极半径及顶盖高度的谐振系统的谐振频率进行仿真,并将仿真结果与理论结果进行对比。理论分析与计算机仿真表明,对于无隔模带磁控管谐振系统,电容耦合使谐振频率随模数的增大而增大,电感耦合使谐振频率随模数的增大而减小;两者分别通过增大和降低模频率从而增大模式分隔度,两者共同作用时模谱图取决于占主导地位的耦合因素。     

W 波段回旋管谐振腔特性参数测量方法的研究*

W 波段回旋振荡管是一种重要的高功率毫米波源,它通常采用圆柱开放式谐振腔作为其高频结构。 谐振腔所具有的特性参数,如谐振频率和品质因数影响了整管的性能。在W 波段,特性参数对于尺寸的变化特别敏 感,因此,有必要对加工好的开放式谐振腔的特性参数进行测量。利用直接耦合法实现了对5 组开放式谐振腔谐振 频率和品质因数的无损检测,实验结果验证了该方法的可行性与有效性。同时,分析了加工误差对谐振腔性能造成 的影响,结果表明,当开放式谐振腔渐变角度的加工误差达到7%以上时,谐振频率将偏移0.2GHz。     

微波线性相位双模介质滤波器

本文讨论了用双模介质加载谐振腔实现的微波线性相位滤波器结构，在非级联耦合的诸振腔之间引入一个交叉耦合，以改善通带内的时延平坦特性，给出了用模匹配法计算介质加载谐振腔的谐振频率和谐振腔之间耦合系数的方法。介绍了采用这种方法构成的滤波器的实际设计方法。最后制作了用这种方法设计出的滤波器，给出的实测结果表明它不仅可满足幅频特性的滤波要求，而且具有良好的通带时延特性。     

Analysis and suppression of SSN noise coupling between power/ground plane cavities through cutouts in multilayer packages and PCBs

The authors introduced a model of simultaneous switching noise (SSN) coupling between the power/ground plane cavities through cutouts in high-speed and high-density multilayer pack-ages and printed circuit boards (PCBs). Usually, the cutouts are used in multilayer plane structures to isolate the SSN of noisy digital circuits from sensitive analog circuits or to provide multiple voltage levels. The noise-coupling model is expressed in terms of the transfer impedance. The proposed modeling and analysis results are compared with measured data up to 10 GHz to demonstrate the validity of the model. It is demonstrated that the cutout is the major gate for SSN coupling between the plane cavities, and that substantial SSN coupling occurs between the plane cavities through the cutout at the resonant frequencies of the plane cavities. The coupling mechanism and characteristics of the noise coupling, from which a method of suppression of the SSN coupling evaluated was also analyzed and discussed. Proper positioning of the cutout and the devices at each plane cavity achieves significant noise suppression at certain resonant frequencies. The suggested suppression method of the SSN coupling was successfully proved by frequency domain measurement and time domain analysis.     

用于铷原子频标的磁控管腔研究

研究了一种应用于铷原子频标的磁控管腔，对用于磁控管腔的主要特征和参数计算进行了研究，主要包括磁控管腔的谐振频率、Q值、微波场模式。研究结果表明磁控管腔的谐振频率可以调谐至6.835GHz，Q值都能够调至600～1000之间，其微波场谐振模式是典型的TE011模式，频率温度系数较小（32.5KHz/℃－35.0 KHz/℃），所设计的磁控管腔能够满足铷原子钟物理部分的设计要求。     

金属腔体多耦合通道电磁特性研究

实际金属腔体常开有多个通道,使得腔内电磁环境变得复杂。以分析腔体多通道耦合电磁特性为出发点,建立平面波入射下矩形、圆柱腔体实例模型,引入对比系数作为评价手段,侧重研究孔缝、贯穿线缆两种耦合通道对腔内电磁场的影响,寻求共性规律。结果表明:腔外线缆长度变化不影响谐振点出现位置,随长度增加腔体屏蔽效能(SE)下降;腔内线缆随长度增加,谐振频率降低,两腔体具有如上共性结论。基于给定的模型及参数设定,通过比较系数可判断矩形腔体450 MHz 之前线缆耦合为主;贯穿线较长时, 510 MHz 之前圆柱腔体线缆耦合为主;贯穿线较短时,两个局部频点之外的其它频段孔缝耦合为主;涂覆磁损耗型吸波材料提升腔体SE 效果最好,且SE越低,提升效果越明显。     

Coupled mode theory of optical resonant cavities

This paper presents a theory describing coupled optical resonant cavities by means of systems of time-dependent coupled equations for the field amplitudes of standing waves in each resonator. The coupling coefficients entering the theory are derived from first principles. To the author's knowledge, this theory is new. The coupling coefficients can approximately be related to the amplitude transmission coefficients of traveling waves passing between the two resonant cavities. This relationship is checked for an example. Finally, we show that the mode amplitudes of one cavity can be eliminated so that the field in the other cavity becomes coupled to samples of itself taken at earlier times. The coupled-cavity theory applies to cavities with loss or gain. It is here expressed in scalar approximation, but it can easily be extended to vector fields.     

双模方形谐振腔增益均衡器的设计与实现

针对均衡器小型化、高Q值的应用需求,提出并设计了一个工作在Ku波段的双模方形基片集成波导谐振腔均衡器.设计了两个正交的耦合缝隙,在谐振腔中激励起简并模TE₂₀₁和TE₁₀₂;使用金属柱微扰其中一个模式,实现独立调节该模式的谐振频率,并且频率调节自由度高;研究了薄膜电阻的加载位置,实现独立调节两个模式的衰减量和Q值;分析了双模谐振腔级联后谐振频率偏移量及可调性,给出了双模谐振腔均衡器的分析和设计方法.相比于传统单模谐振腔均衡器,该结构均衡器保持了原有的工作性能,并减少了一半数量的谐振腔,使得结构更加紧凑.测试结果与仿真结果吻合,最大误差0.4dB.     

Dual mode coupling by square corner cut in resonators and filters

A method for realization of dual-mode coupling in rectangular waveguide cavities is described and analyzed. The method completely replaces the coupling screw, and therefore can be used to eliminate the need for tuning in dual-mode waveguide cavity filters. It also offers a wide range of coupling values and can achieve higher power-handling capability than coupling screws. Mode matching is used to calculate the mode chart of the infinitely long square corner cut rectangular waveguide (SCCRW), the field distributions of each mode, and the resonant frequencies of the cavity. An evanescent mode rectangular waveguide is used to provide dual-mode couplings between adjacent cavities. The junction discontinuity between the SCCRW and the rectangular waveguide is modeled by a double mode-matching method, yielding modal scattering parameters of the junction. A four-pole dual-mode elliptic-function rectangular waveguide cavity filter using the coupling method was constructed. The experimental filter results showed excellent agreement with theory     

Frequency dependence of the coupling coefficients and resonant frequency detuning in a nanophotonic waveguide-cavity system

Waveguide-cavity interactions may find important applications in future nanophotonic devices. This paper provides a detailed derivation of the evolution equation of the amplitude of a cavity mode coupled to a waveguide, starting from Maxwell's equations and using the reciprocity relations. The analysis applies to both constant cross-section and periodic waveguides as well. Unlike previous studies, the analysis enables the estimation of the frequency dependence of the coupling coefficients. It is also confirmed that the waveguide-cavity coupling causes a detuning of the resonant frequency of the cavity mode. The detuning is estimated in the case of a photonic crystal waveguide-cavity system and it is shown that it can be significant especially if the structure is intended for filtering applications. The analysis is generalized to the case of a multimode or multiple cavities and provides a useful tool in the analysis of devices based on coupled cavities.     

Tripartite entanglement properties in the system of atoms interacting with three coupled cavities

It is considered that three identical two-level atoms are separately trapped in three coupled single-mode optical cavities, and each atom resonantly interacts with cavity via a one-photon transition. The tripartite entanglement dynamics among atoms is studied. The influence of cavity-cavity coupling constant on the tripartite entanglement among atoms is discussed. The results obtained using the numerical method show that the tripartite entanglement among atoms has a nonlinear relation with the cavity-cavity coupling coefficient. On the other hand, the three-body entanglement is the result of the coherent superposition of the two-body entanglements.