基于SAW谐振器无源无线传感器编码方法研究

为简化声表面波(SAW)传感器的编码过程,提出了一种基于SAW谐振器的编码方法,通过多个不同中心谐振频率的SAW谐振器分别连接不同的负载阻抗进行传感器的编码。设计了传感器的具体结构,建立了传感器的等效电路模型,利用ADS仿真软件对中心谐振频率分别为868MHz和915MHz的2个SAW谐振器组成的传感器进行仿真,结果表明,SAW谐振器外接1pF与4pF的阻抗,其谐振频率差可达200³00kHz。根据仿真结果,设计制作了不同编码的2个传感器,一个不外接阻抗,一个外接10pF的阻抗,测试谐振频率差别可达39.75300kHz。根据仿真结果,设计制作了不同编码的2个传感器,一个不外接阻抗,一个外接10pF的阻抗,测试谐振频率差别可达39.75⁴0.2kHz,因此,SAW谐振器外接不同阻抗时谐振频率的差异明显,基于SAW谐振器与外接阻抗的传感器编码方法是可行的。     

A Design Method of Bandpass Filters Using Dielectric-Filled Coaxial Resonators (Short Papers)

Design formulas for capacitively coupled bandpass filters using dielectric-filled coaxial resonators are derived and experimentally verified. The most important advantage of this filter is its ability to provide wide stopband characteristics for harmonics suppression. Its features can be obtained from the configuration using both quarter-wavelength uniform impedance resonators (UIR's) and stepped impedance resonators (SIR's).     

Study of Eigenmodes of Coaxial Resonators Using Coupled-Wave Theory

Based on the surface impedance theory (SIT) and the coupled-wave theory (CWT), this paper has established the second-order transmission line equation applicable to coaxial resonators with corrugated inner conductor. By utilizing the equation, the resonant frequency, Q factor and field profiles geometry of the eigenmodes of coaxial resonators can be calculated in view of the mode coupling, and the variables of the slot width and depth in the coupling coefficient can also be applied to calculate their impact on the resonant frequency and Q factor. The numerical results show that, the slot width and depth have significant impact on the resonant frequency, but their effect on Q factor is approximately negligible.     

压电陶瓷圆筒振子耦合振动的本征频率分析

研究了压电陶瓷圆筒振子的耦合振动,分析了振子的轴向、径向伸缩振动及扭转振动之间的耦合关系.从理论上推导出了振子耦合振动的共振频率方程.由于分析中对振子的几何尺寸未加任何限制.因此所得结论适用于任何尺寸的陶瓷圆筒振子,其中包括厚壁圆筒及圆环.理论分析表明.本研究计算简单,物理意义明显,与一维理论的结果相比,文中得出的振子耦合振动的共振频率与实测值符合较好.     

Characteristics of single and coupled rectangular resonators in suspended substrate stripline

A rigorous spectral-domain analysis is carried out to determine the resonant frequency characteristics of resonators in a general suspended substrate stripline. The resonant frequency characteristics of single as well as coupled rectangular resonators are computed. An important observation for resonators in broadside-coupled suspended substrate stripline is that the even- and odd-mode resonant frequencies are considerably different.     

Dual- and Triple-Mode Branch-Line Ring Resonators and Harmonic Suppressed Half-Ring Resonators

Ring resonators have been widely used for various applications. Dual-mode ring resonators have also been investigated due to their applicability to multifrequency mode requirement. In this paper, dual-mode ring resonators using a branch line are designed along with a systematic approach. Triple-mode branch-line ring resonators are also designed adding two branch lines to the ring resonator. Adding more branch lines, multimode resonators can be realized based on the design procedure developed here. The location of the branch lines determines the additional resonant frequencies other than the fundamental resonant frequency generated by the enclosing ring. Furthermore, half-ring resonators working at 2.5 GHz are proposed for suppressing multiple harmonics (second and third harmonics) and providing size reduction with employment of various physical configurations. Equalizing the even- and odd-mode phase delays, harmonics are suppressed effectively in the design of half-ring resonators. Double half-ring resonators with a long opening gap are investigated to continuously decrease the resonant frequency. An open-loop structure provides flexible design and lowers the resonant frequency. Two dual-mode ring resonators and one triple-mode ring resonator are simulated and fabricated along with three different half-ring resonators     

Design of Microwave Dielectric Resonators

The resonant frequencies for the fundamental modes in circular cylindrical and rectangular parallelopiped high dielectric resonators have been calculated by computer for a range of values of physical dimensions and relative dielectric constant. The frequency range extends from zero to 50 kMc/s, the relative dielectric constant from 50 to 1800, and physical dimensions from zero to 500 roils. Results are presented in graphical form with frequency plotted vs. resonator length for parametric values of relative dielectric constant and cross-sectional dimensions. A brief review of earlier work with high dielectric resonators is included. Expressions for the resonant frequency and fundamental mode field configurations are given.     

GIBC formulation for the resonant frequencies and fielddistribution of a substrate-mounted dielectric resonator

Dielectric resonators (DR's) are widely used in telecommunication systems. A method is proposed here to find the resonant frequency and field distribution in a substrate-mounted DR structure. The field of a dielectric rod has been decomposed into a combination of guided modes with unknown coefficients and an unknown continuous spectrum of radiation field. The unknowns are then obtained by applying two generalized impedance boundary conditions (GIBC's) representing the substrate and air layers at the top and bottom of the DR. This leads to the calculation of the total (guided+radiation) field as well as the resonant frequency of the structure     

谐振法确定热激励微梁谐振器厚度及残余应变

精确测量热激励微梁(悬臂梁和桥)谐振器的厚度和残余应变对研究其谐振特性具有重要意义。由于组成谐振器的薄膜厚度远小于占优层厚度，本文首先利用单层梁谐振频率推算得梁的厚度的近似值，从而得到热激励梁的等效杨氏模量和等效密度。在此基础上利用双层梁谐振频率精确推算梁的厚度和残余应变，结果与测量值符合较好。该方法具有非破坏性的优点。     

Analysis and Composition of a New Microwave Filter Configuration with Inhomogeneous Dielectric Medium

A theoretical study has been undertaken to solve inter-resonator coupling problems, and to design a new structure of microwave bandpass filter. This filter is composed of quarter-wavelength resonators arranged in a housing with the same ends short-circuited. This arrangement of resonators has never been utilized to compose bandpass filters because of the small inter-resonator coupling. The coupling coefficient of TEM resonant lines has been derived theoretically and expressed with capacitive parameters of the coupled lines. The accurate values of capacitances of the lines were obtained by the numerical analysis of the TEM field. By a simple method to make the medium inhomogeneous through removing the dielectric partially, a simplified structure of filter has first been realized based on the theory. Through numerical analysis by the finite difference method, this structure is also shown to have higher unloaded Q of resonator than conventional dielectric-filled coaxial filters to minimize the volume of filters.     

Compact left-handed microstrip line based on multiple layered step impedance resonators

A novel compact left-handed (LH) microstrip transmission line is presented. To establish a negative permeability and permittivity, the transmission line is loaded with step impedance resonators (SIRs) and an array of thin wires on dual-layer architecture. Compared to existing LH structures, which incorporate conventional split ring resonators (SRRs), the proposed structure is three times smaller in size whilst achieving the same performance. To illustrate the electromagnetic properties of the metamaterial, both analytical and full wave analysis were performed and utilized to determine the effective electromagnetic parameters of the proposed structures. The experimental results show that a microstrip line periodically loaded with SIR only produces a rejection of ?6?dB at a resonant frequency of 5.50?GHz. The results also indicate a pass-band response for a left-handed microstrip line (LHML) constructed from SIR and thin wire arrays at the same resonant frequency.     

Design of Miniature Planar Dual-Band Filter Using Dual-Feeding Structures and Embedded Resonators

A new dual-band planar filter has been proposed. It is shown that the two transmission bands can be excited and designed using proposed resonators which combine different sizes of open-loop resonators. The main resonators control the low-band resonant frequency and the sub resonators control the high-band resonant frequency. With dual-feeding structures added, the performances of the filter such as frequency selectivity and insertion loss are much improved. The embedded resonators structure can further miniaturize the dimensions of the overall structure. The proposed dual-band filter will find applications in wireless communication circuits     

Compact UWB PCML bandpass filter with L- and C-shaped resonator

A novel ultra-wideband (UWB) bandpass filter with four resonant modes is proposed based on a parallel coupled microstrip line (PCML) with L- and C-shaped resonators. The coupling factor of the PCML structure depends on the impedance of the feeding network. The PCML coupling factor can be enhanced by using a feeding network with smaller characteristic impedance. With an L-shaped feeding network and C-shaped middle microstrip line a non-uniform resonator is constructed with the first two resonant modes falling within the UWB. The other two resonant modes within the UWB can be obtained by adjusting the width of both the L- and C-shaped resonators. Overall the designed filter exhibits good UWB passband behaviour with insertion loss < -0.2 dB and group delay < 0.15 ns.     

Analytic design of conformal slot arrays

A completely analytic design process has been developed for small slot arrays which accounts for the varying effect of mutual coupling as a function of element position. A previously developed theory for the design of small arrays has been extended to include conformal dielectric-filled waveguide slot arrays. Computer software has been assembled which enables calculation of the slot geometries required to implement a specified aperture distribution and input impedance condition. The slot self- and mutual admittances are calculated numerically, thus eliminating the traditional measured slot data from the design process. This design technique has been applied to conformalX-band slot arrays on cylinders of a few wavelengths diameter. The arrays consist of multiple dielectric-filled waveguides, each of which is a narrow-band standing-wave linear array of longitudinal shunt slots. The computerized design process adjusts the length and offset of each slot in the total array until the desired aperture distribution and impedance match are achieved. A flow diagram of the design program and test results from experimental arrays are presented.     

A study of the nonorthogonal FDTD method versus the conventionalFDTD technique for computing resonant frequencies of cylindricalcavities

The nonorthogonal finite-difference-time-domain (FDTD) technique is used to compute the resonant frequencies of dielectric-filled cylindrical cavities. Because the method is based on the nonorthogonal coordinate system, it is not restricted to specific geometries, e.g. rectangular or axially symmetric geometries, and is suitable for analyzing cavities of arbitrary shape. The advantages of this technique over the conventional FDTD algorithm with a staircase grid are shown in a convergence study, where the two methods are used to compute the dominant resonant frequency of a cylindrical cavity. The accuracy of the technique for calculating the resonant frequencies of the first few modes is demonstrated by comparing the results obtained with this technique with those derived by using two versions of the finite element method in the frequency domain     

水平静电驱动式多晶3C-SiC折叠悬臂梁谐振器微结构

介绍了一种微机械叉指静电驱动折叠悬臂梁谐振器的设计和制作方法.将Rayleigh分析法和有限元分析法结合起来分析调整器件尺寸和材料参数对器件性能的影响.制作了三种不同悬臂梁宽度的微机械横向谐振器件,经实验检测它们的谐振频率分别为64.5,147.2,255.5kHz,与模拟结果符合得很好.该结果显示由于具有很高的杨式模量,利用多晶3C-SiC材料体系制作的谐振器件能够具有更高的谐振频率.     

Astigmatic Gaussian beams produced by axially asymmetric laser cavities

Gaussian beams generated within astigmatic resonators are themselves astigmatic, having wavefront curvatures and spot sizes that are different when measured in two orthogonal directions. Expressions are derived for the confocal parameters, spot sizes, waist positions, and stability conditions of beams formed within spherical mirror resonators that contain one or more inclined plates (or Brewster-ended laser rods). An expression is also derived for the resonant frequencies of the TEMmnmode in such a resonator. It is shown that the frequency degeneracy between modes of the samem + nis lifted and the frequency splittings are calculated. The astigmatism produced by prisms used for dispersion is also considered and precautions are described for avoiding serious astigmatism in resonators containing such prisms.     

Resonant modes in shielded uniaxial-anisotropic dielectric rodresonators

Rigorous field analysis by the mode-matching method is presented for dielectric rod resonators, including such uniaxial dielectrics as sapphire, which are placed between two parallel conducting plates or in a conducting cavity. The wave equations for E_Z and H_Z in a uniaxial anisotropic dielectric medium are derived in a cylindrical coordinate system. Based on these wave equations, the characteristic equations for the two resonator structures are derived and can be used to calculate the resonant frequencies of any resonant mode. Cutoff conditions of the resonant modes are discussed for parallel-plate-type resonators. Resonant frequencies of some lower order modes are calculated for both types of resonator. Mode charts useful for designing the resonators are presented. It is verified that the mode-matching method used commonly for the analysis of isotropic-dielectric resonators can be applied successfully to uniaxial-dielectric resonators     

The dielectric-filled tubular monopole

The integral equation for the current in a dielectric-filled tubular monopole when driven by a coaxial line with an assumed pure TEM mode is formulated and solved by a numerical method. It is found that when the dielectric-filled tube can support a TM01circular waveguide mode, the characteristics of the antenna are drastically different. In this case a very sharp resonance behavior is observed. The resonant length depends primarily on the properties of the internal waveguide mode rather than on the free-space behavior of the antenna.     

平面螺旋带线谐振器谐振频率的计算

提出了一个用来模拟、分析和计算平面螺旋带线谐振器谐振频率的物理模型和方法。借助该模型，采用矩量法计算了螺旋带线上的电荷分布，进行计算出平面螺旋带线谐振器的分布电容，从而得到其等效电路参量并最终计算出谐振频率，计算结果与实验数据十分一致。