NUMERICAL MODELING OF OPTICALLY CONTROLLED DIELECTRIC REASONATORS

To analyze the optically controlled dielectric resonators accurately, an efficient numerical modelling technique is proposed in this paper. By using alternating-direction implicit finite-difference time-domain method and conformal technique, the resonant frequency of a dielectric resonator is calculated. In addition, an optical generation of plasma is used as a possible means of controlling the resonate frequency, and the effect that solid state plasmas have on the resonator’s frequency is described. The numerical results agree very well with measurements in estimation of the optically induced resonator’s frequency-shift.     

2200 MHz圆环形介质谐振器的研制

讨论了TE011谐振模式的圆环形介质谐振器的研制过程。固定ZnO添加量为质量分数1.00%,考察了WO3改性剂对(Zr0.8Sn0.2)TiO4微波陶瓷介电性能的影响。当w(WO3)为0.25%时,可得到εr为38.0、Q值大于5800(7GHz)、τf小于2.0×10–6/℃的瓷料。以该瓷料为原料制作谐振器,研究了制作工艺和支撑物高度对谐振器性能的影响。发现采用冷等静压成型工艺所制谐振器的Q值比采用干压成型工艺提高了4%。获得了谐振频率为2200MHz的高Q值、高功率、高稳定性圆环形介质谐振器,完全满足设计要求。     

Improvement of accuracy in measurements of the surface resistanceof superconductors using dielectric resonators

Two techniques to minimize the influence of parasitic losses on surface resistance measurements of superconductors employing dielectric resonators have been described. The first method optimizes the sapphire resonator aspect ratio to minimize the parasitic losses for given superconductor sample dimensions and measurement frequency. The second utilizes a reference resonator with a perfect conductor plane to cancel out the influence of parasitic losses by measurements of the resonant frequencies and Q-factors of two resonators. The second technique is recommended when materials having noticeable dielectric losses are used to construct dielectric resonators     

厘米波段介质带通滤波器的设计与制作

为了提高基站的通信质量,研制了高性能的窄带介质带通滤波器。选择切比雪夫低通原型设计线路,采用6个环形介质谐振器直接耦合实现滤波器,输入输出采用探针耦合。用HFSS软件对滤波器的结构进行了仿真。用εr=38的高Q值介质陶瓷材料制作了环形谐振器,分析了衬垫材料的高度对环形谐振器性能的影响,测试了级间耦合系数。最后制作出中心频率为6GHz的介质带通滤波器,滤波器的带宽窄（0.5%）,插入损耗较小,阻带衰减很高,达到了国内先进水平。     

Dielectric resonator with discrete electromechanical frequency tuning

A novel approach for discrete frequency tuning of dielectric resonators based on electromechanical actuators such as the microelectromechanical system is presented. The concept is based on the intermodal coupling between the TE/sub 01/spl delta// mode of a cylindrical dielectric resonator and the radially arranged planar slotline resonators. The resonance frequency of the dielectric resonator is changed by switching a resistive load at the open end of each quarter-wave slotline resonator leading to a variation of the coupling between the slotline resonator mode and the TE/sub 01/spl delta// mode of the dielectric resonator. As a consequence, the resonance frequency of the TE/sub 01/spl delta// mode changes. Based on this novel tuning concept, discrete tuning by 5 MHz in 0.25-MHz frequency steps was demonstrated for a test resonator at 2 GHz. The unloaded quality factor is about 12000 and the measured switching time is about 1 ms.     

Tunable, temperature-compensated dielectric resonators and filters

A thermal and electromagnetic model of a tunable hybrid-mode dielectric double resonator is introduced and analyzed by the mode-matching technique. Results of the analysis show the temperature sensitivity of the structure as a function of the center frequency as well as the other resonator parameters. A simple optimization procedure which allows the design of the resonator to have both a wide tunability range and good thermal stability of the resonant frequency is described. A circuit model is presented for a tunable four-pole dual-mode filter. The model exhibits interesting dual passbands, separated by a very-high-attenuation stopband. Measured results obtained from an experimental four-pole dual-mode dielectric resonator filter designed using the tunable hybrid-mode resonators showed excellent tunability range (200 MHz at C-band) and good agreement with the circuit model     

厚度伸缩压电陶瓷振子

对厚度伸缩压电陶瓷振子的振动状态进行了分析,并得到其等效电路.推导了振子的谐振频率、反谐振频率以及等效电路参数与振子尺寸、振子材料的介电、压电、弹性常数间的关系式.最后讨论了振子的一些特性和制作.     

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.     

Modified method for the analysis and design of microwave bandpass filters containing dielectric resonators

High-Q dielectric resonators having remarkable advantages such as compactness, light weight, temperature stability, and low cost have become very valuable elements for various microwave circuits. A modified Itoh and Rudokas model is proposed to analyse the field distribution and the coupling relations between dielectric resonators and microstrip lines based on the analysis results, a convenient procedure for designing microwave filters containing parallel coupled dielectric resonators is presented. Two experimental dielectric resonator filters are also fabricated to verify the calculation and the design procedure. The outcome demonstrates that the procedure provides good accuracy and saves design time.     

高阻带微波带通滤波器的研制

为了提高通信设备的性能,研制了高阻带的微波滤波器。该滤波器由5个高Q值的同轴介电陶瓷谐振器构成的带通滤波器。谐振器之间通过介电基片上的电容相互耦合。在装入外壳前,调整好每个谐振器的谐振频率和耦合电容,之后就不需要再调整,外壳上也没有可调零件,从而保证滤波器结构稳定,性能可靠。用εr=74的介电陶瓷制作出滤波器的性能为f0=982 MHz,Δf=10.9 MHzI,L=3.8 dB,阻带在f0±30 MHz处大于69 dB,远阻带衰减优于70 dB。     

源与负载感性交叉耦合的小型介质滤波器

为了提高滤波器的阻带衰减,研究了源与负载感性交叉耦合的小型介质滤波器。首次提出一种新概念：将源和负载看作准谐振器。以贴片电感作为源与负载之间、源与第二个谐振器之间的交叉耦合元件,两个准谐振器和两个介质谐振器可构成级联四节(CQ),一个准谐振器和两个介质谐振器可构成级联三节(CT)。分析了传输零点的位置,详细讨论了这种滤波器结构的设计方法。采用介电常数为80的介质陶瓷组装了3个两级介质滤波器,并进行测试,结果表明传输零点的个数和位置与仿真设计相符合。滤波器的体积小,均为14 mm×6.5 mm×10 mm。     

Characteristics of double-dielectric fin-line resonators

Broadside-coupled and broadside edge-coupled slot resonators in a fin-line using two dielectric substrates with an intervening air gap have been analysed using the spectral-domain technique. Numerical results on the resonant frequencies of structures with single as well as coupled resonators on each substrate are reported as a function of the air gap and other structural parameters. The resonator patterns on the two substrates are mirror images of each other. Coupled configurations include parallel-coupled, parallel-coupled offset, and end-coupled resonators on each substrate. The resonant frequency has been measured as a function of slot width for the case of a single resonator on each substrate. Agreement with the computed results is found to be good.     

Resonant Frequency Stability of the Dielectric Resonator on a Dielectric Substrate

A simple approximate method for predicting the resonant frequencies of TE modes of dielectric resonators is developed. By using this method, an analytical expression is derived for the resonant frequency stability of the dielectric resonator on a dielectric substrate, and the effect of the substrate on the stability is studied. The result is useful when the high-frequency stability is required.     

非均匀介质谐振器的谐振频率分析与FDTD方法

为了揭示非均匀介质谐振器的谐振频率与非均匀介质的特性之间的关系,首先基于Matlab编码,应用时域有限差分法(FDTD),对一个均匀介质的谐振器进行了模型分析和结果仿真,与实测结果对比,仿真结果显示了FDTD方法的有效性。然后建立一个具有横向平面分层式结构的非均匀介质谐振器模型,通过调节各层介质不同的厚度比例,发现可以用两种固定的介电常数相异的介质来获取所期望的谐振频率。这个分析和模拟结果有助于设计模型简单、尺寸规格相近但谐振频率各异的介质谐振器。     

Whispering gallery modes in a dielectric resonator:characterization at millimeter wavelength

Applications of whispering-gallery-mode (WGM) dielectric resonators in the millimeter and submillimeter frequency range are discussed. A summary of the main peculiarities of these resonators is given, and a method to obtain approximate analytical expressions of electromagnetic field components is developed. Problems connected with the excitation by far infrared (FIR) laser radiation are examined. The analysis of electromagnetic propagation in different structures drives the best choice for the transmission line (metallic and dielectric waveguides), and the same theoretical analysis allows to face the basic problem of optimizing the matching between transmission-line and WG resonators; the role in this application of dielectric waveguides with variable diameter is discussed. All of the predictions are obtained in a unified theoretical picture. The experimental characterization of a WG resonator at 240 GHz involved the measurement of the effectiveness of the coupling between the transmission line and the resonator, the determination of the merit factor and free spectral range for the different resonance families in different resonators. Accurate measurements were carried out to acquire knowledge of the field distribution in both axial and radial directions; to this purpose, dielectric antennas with high directivity were used to sense the field intensities for different resonance modes. The good agreement between the experimental results and the theoretical predictions is carefully discussed     

介质同轴谐振器的频率测试方法

介绍了一种测量介质同轴谐振器频率的新方法，即在谐振器的开路端串联一高品质因数Q电容，用标量网络分析仪测出其串联谐振频率，从而得出谐振器的频率。该方法操作简单，对仪表的要求不高，适合于规模生产，特别适合于介质滤波器的调试。     

A low-loss bandpass filter using electrically coupled high-Q TM01δ dielectric rod resonators

For a TM_01δ mode dielectric rod resonator placed coaxially in a TM₀₁ cutoff circular waveguide, characteristics such as the resonant frequency, its temperature coefficient, the unloaded Q, and the other resonances are discussed on the bases of accurate calculations using the mode-matching method. The results show that this resonator compares favorably with a conventional TE_01δ mode dielectric resonator, particularly for realization of a high unloaded Q. Analytical results also verify that interresonator coupling between these two resonators can be expressed equivalently by a capacitively coupled LC resonant circuit. A four-stage Chebyshev filter having a ripple of 0.035 dB and an equiripple bandwidth of 27 MHz at a center frequency of 11.958 GHz was fabricated using these resonators. Its insertion loss is 0.5 dB, which corresponds to an unloaded Q of 17000, and no spurious response appears in the frequency range below 17 GHz     

Bandpass filters using dual-mode and quad-mode Mobius resonators

Compact bandpass filters are being developed using Mobius wire-loaded cavity resonators. Initial results on tuned filters indicate that excellent filter characteristics can be attained in devices that are significantly smaller than traditional wire-loaded cavity technologies. A novel quad-mode Mobius resonator is presented which occupies the same volume as a dual-mode Mobius resonator. A four-pole bandpass filter is demonstrated using a single quad-mode Mobius resonator. Precisely controlled dielectric loading of dual-mode Mobius wire resonators has been implemented to realize bandpass filters. Two-pole and four-pole bandpass filters are demonstrated using one and two dual-mode dielectric-loaded Mobius resonators, respectively     

Helical Resonators for Measuring Dielectric Properties of Materials

A theoretical and practical investigation is given of superconducting helical resonators with quality factors greater than 10/sup 8/ which allow the determination of dielectric loss tangents in the frequency range of 0.1 to 5 GHz and below 15 K with high accuracy. The underlying measurement theory is an extension of perturbation theory. They are evaluated for the fields in a shielded multiple quarter-wave helical resonator with a cylindrical dielectric specimen inside the helix. Measurement results on optimized resonators made from superconducting Nb and Nb/sub 3/Sn are reported as well as further applications.