Weakly Coupled Dielectric Resonators

The resonant modes of a pair of coupled resonators of high epsilon/sub r/ are considered in the limit of large spacings D between resonators. Attention is focused on the lowest "magnetic-moment" mode, where the coupling effect leads to a split of the original mode into an even and an odd part. Formulas are obtained for the coupling coefficient, the resonant frequencies and Q of the modes. They are strikingly similar to those for weakly-coupled R-L-C circuits. The accuracy of the formulas is verified by comparing their predictions with direct numerical data, available for coupled circular cylindrical 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.     

The Excitation of Dielectric Resonators of Very High Permittivity

The response of a dielectric resonator excited by either interior volume sources or incident exterior waves is investigated. Special attention is devoted to phenomena at resonace, and in particular to the induced electric and magnetic dipoles. Simple formulas are obtained for the scattering cross section. The material of the resonator is assumed lossless and of very high permittivity.     

Accurate Resonant Frequencies of Dielectric Resonators

The applications of dielectric resonators are currently of considerable interest in microwave integrated circuits. The design of a dielectric resonator depends on its natural resonant frequencies. Since exact solutions of dielectric rectangular and cylindrical resonators cannot be rigorously computed a new and more accurate method has been developed to solve this problem. In this method all the surfaces are simultaneously considered as imperfect magnetic walls. Theoretical values agree very well with experimental results. The difference being less than 1 percent.     

Circuit Properties of Microwave Dielectric Resonators

The purpose of this paper is to present experimental data on the circuit properties of dielectric resonators which do not have conducting boundaries. The resonators are constructed of single-crystal rutile and strontium titanate, which, as has been shown by several authors, can form resonators of miniatnre size and high unloaded Q. We consider the lowest-order H mode, give measured values of resonant freqnency (for rectangular parallelepipeds), mechanical frequency tuning, control of coupling to microwave circuits, and discuss the measurement of, and typical values of, external Q of resonators mounted in waveguides. We also consider periodic propagating circuits consisting of linear arrays of mutually coupled resonators.     

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。     

Edge Diffraction Suppression in Rectangular Dielectric Resonators for Quality Factor Enhancement Using Artificial Plasma

The concept of quality factor enhancement in a two dimensional rectangular dielectric resonator (RDR), based on the phenomenon of edge diffraction suppression by a plasma, is presented. This phenomenon occurs when the plasma exhibits the specific negative permittivity, which makes the RDR separable, i.e., analytically solvable by means of the separation of variables. The Rotman plasma, constituted of metal thin wires is proposed as a practical implementation of this ideal plasma, and the diffraction suppression concept is demonstrated with this plasma by an SIE/MoM approach verified by using a finite element method solver, HFSS. It is shown that a relatively small number of wires (4 $,times,$4) in the plasma is sufficient to mimic a close-to-ideal plasma medium, which suggests a potential for practical applications. This study reveals that the utilization of this plasma allows a strong (high-$Q$ ) resonance even for low-permittivity dielectrics otherwise improper to act as resonators.      

Analytical and Experimental Considerations on the Resonant Frequency and the Quality Factor of Dielectric Resonators

A dielectric pillbox resonator placed on a dielectric substrate is analyzed by a new method, the approximate mode matching method, in which the cross section of such a resonator is subdivided into several sub-sections having a simple geometry of the boundaries, i.e., dielectric slab radial waveguides, and the continuity condition of fields between subsections is treated in the least-squares sense. The resonant frequencies and the intrinsic Q values due to the leakage loss through the dielectric substrate calculated by this method are presented together with experimental results obtained in the 50-GHz region. As a result, it is found that the experimental results for both the resonant frequencies and the Q values agree better with our calculated ones than with the results by other approximate method, and so it will be concluded that the analytical method presented here is almost enough to discuss precisely the resonant characteristics of a dielectric pillbox resonator.     

Electromagnetic Analysis of Spherical Dielectic Shielded Resonators (Short Paper)

We present in this paper, the electromagnetic parameters of free and shielded dielectric spherical resonators for their utilization in the millimeter-wave frequency band.     

Application of Dielectric Resonators in Microwave Components

Dielectric resonators are being used in microwave filters and oscillators now that high-dielectric-constant, high-Q, temperature-stable ceramics have been developed. This paper reviews dielectric resonators with emphasis on applications, contains tutorial material, deseribes new 2-, 4-, and 6GHz bandpass filters, and presents several examples of oscillator applications. A complete blbliography to English language publications on dielectric resonators is included.     

介质谐振器稳频的微波自振混频器

介绍了利用介质谐振器稳频,用场效应管(FET)或双极型晶体管制成的微波自振混频器的工作原理、实验电路及测试结果。实验表明,在X波段使用FET混频器变频增益达5.8dB,噪声系数为13.0dB。在C波段使用双极型晶体管,获得变频增益为4.8dB。     

Study on BMT Millimeter Wave Dielectric Resonators

The microwave dielectric properties and microstructures of Ba(Mg_1/3Ta_2/3)O₃ (BMT) ceramics were investigated. In order to reduce the evaporation of MgO at high temperature, burying in MgO powders sintered BMT ceramics. The relationship between the composition and Q value of BMT ceramics was discussed. Dielectric resonators using in millimeter wave band have been designed and fabricated. Their attenuations at central resonation frequency (τ_f) are less than 35dB. Temperature coefficients of resonant frequency are adjustable and less than 2 ppm/°C.     

Microwave Bandpass Filters Containing High-Q Dielectric Resonators

This paper is concerned with dielectric disks used as resonators in microwave bandpass filters. For many years it has been known that modes of resonance occur in isolated dielectric bodies having air boundaries, and that very compact high-Q resonators can be achieved when /spl epsiv/ /sub r/, is high and tan /spl delta/ is low. High-purity TiO/sub 2/ ceramic material, for example, has an /spl epsiv/ /sub r/ about 100, tan /spl delta/ about 0.0001, and Q/sub u/ about 10 000. Practical applications of dielectric resonators have previously been limited by insufficient design information. Formulas are derived for the coupling coefficient between adjacent dielectric-disk resonators within a metal waveguide below cutoff. This metal enclosure is necessary for shielding and to prevent radiation loss. Comparisons between theoretical and experimental coupling coefficient values show very good agreement in each of the three bandpass configurations treated in this paper. Techniques of loop and probe coupling to the end resonators of a multiresonator bandpass filter are discussed and methods of supporting the resonators are suggested. The conclusion is made that microwave dielectric resonators offer important size reductions compared to conventional resonators of similar high Q, but that the center-frequency change of the dielectric resonators as a function of temperature is excessive for many applications. Temperature stabilization is one solution, but preferably a material should be developed having electrical characteristics similar to TiO/sub 2/ ceramic, but with at least an order of magnitude improvement in temperature sensitivity.     

介电常数对介质谐振器调频工作效率的影响

当介质材料的εr一定时,谐振器的频率与其高度成反比。通过试验发现:当谐振器的频率相同时,采用低εr的介质材料,可以降低研磨加工所需的精度要求,从而提高调频的工作效率。采用εr=40介质材料制成1 500 MHz的谐振器,当高度误差为±0.01 mm时,频率误差小于3 MHz;如果采用εr=90的材料,则超过5 MHz。     

Analysis of Microstrip Circuits Coupled to Dielectric Resonators

A lumped element circuit model is introduced to represent coupling between a cylindrical dielectric resonator and a microstrip line. The external Q of the structure is computed and compared to experimental data obtained with three different resonators.     

Design of Cylindrical Dielectric Resonators in Inhomogeneous Media

An iterative analytical method is presented for computing resonant frequencies of dielectric cylindrical resonators in inhomogeneous media. Normalized design charts are presented including a wide range of practical geometrical and physical parameters. Numerical results, when compared to three independent sets of experimental data, show an accuracy of better than 1 percent.     

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.     

Complex Response Function of Whispering Gallery Dielectric Resonators

A whispering gallery resonator coupled to a dielectric waveguide is experimentally investigated around 86 GHz using a vectorial network analyzer. The resulting complex response function is compared with a theoretical model, simplified assuming negligible stationary waves; indeed their presence can be effectively compensated by a proper normalization procedure, made possible by a suitable analysis in the complex field. It is demonstrated that the proposed approach well reproduce the experimental results in a wide range of coupling conditions. Moreover, some outcomes of the model concerning the power flowing into the resonator are briefly discussed.     

小型介质同轴谐振器的设计与制作

阶梯阻抗结构可以有效地降低同轴谐振器的高度,阶梯阻抗同轴谐振器的各段长度一般是通过求解谐振条件方程式来确定,计算过程繁琐。首次用Smith圆图辅助设计其结构尺寸,非常简单,选择参数相当直观。设计了一中心频率为930MHz,阻抗比为0.172的介质同轴谐振器,其总长度约等于八分之一波长。采用εr=88的微波介质材料制作了实物,并用网络分析仪测试其频率,测试结果与设计数据基本吻合。     

Computed Modal Field Distributions for Isolated Dielectric Resonators

Electric- and magnetic-field patterns for five of the lowest resonant modes in cylindrical dielectic resonators are displayed in various planes of intersection. The computational procedure is based on a method moments solution of the surface integral equation for bodies of revolution. Improvement of the numerical stability through the normalization of the matrix is discussed, and an algorithm for the evaluation of the modal field components is described.