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。     

The Q-Factor of Coaxial Resonators Partially Loaded with High Dielectric Constant Microwave Ceramics

The quality factor of partially loaded dielectric coaxial stepped impedance resonatop (PDSIR) has been analyzed, including analysis of the dielectric constant epsilon/sub r/ and the dielectric loss tan delta of the ceramics. The Q-factor of several resonators is also calculated and compared with the experimental results. This shows that the Q-factor degradation lessens even though the resonator length becomes small when the total length L/sub t/>1//spl radic/epsilon/sub r/ and becomes large when L/sub t/ < 1//spl radic/epsilon/sub r/.     

Bandstop Filter in Nonradiative Dielectric Waveguide Using Rectangular Resonators

A bandstop filter realized by means of rectangular resonators coupled to the center dielectric strip of a nonradiative dielectric (NRD) waveguide is described.This filter has the advantage that it is simple to manufacture, making use of a center dielectric of standard cross section. The design procedure is similar to the conventional strip line design procedure, with the stubs replaced by "stubs" of dielectric, or resonators. The design equations for the stub coupling are derived the properties of the stubs are obtained through measurement.     

新型高温超导(HTS)双模多次曲折微带环窄带滤波器

发展了一种新型HTS双模多次曲折微带环谐振器滤波器.给出了双模间耦合系数的精确计算方法.采用全波技术对四极滤波器特性进行的计算表明,它具有优良的窄通带、高选择性和小体积.设计、制造和测试了一个HTS四极滤波器,实验结果与理论计算基本一致.这种滤波器适用于卫星通信和移动通信系统.     

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.     

A Miniature High-Q Bandpass Filter Employing Dielectric Resonators

The miniaturization of high-Q resonant microwave structures is of great importance. This must he done to keep pace with the size reduction of other related components. The need has led to an investigation into the feasibility of using dielectric materials as microwave resonators. This paper deals with the application of the TiO/sub 2/ dielectric resonator in a narrowband bandpass filter operating in the 2200 to 2300 MHz telemetry band. The study confirms the theory that a bandpass filter employing dielectric resonators is practical to build, is compact, and will approach the performance of an equivalent waveguide filter. The design employed five resonators mounted in a cylindrical tube that was 1.4 inches in diameter by 4.3 inches long and weighed 4.6 ounces. An equivalent waveguide filter would be approximately 2.3x4.5x16 inches long and would weigh approximately 64 ounces (WR-430). The thermal sensitivity of the dielectric resonator employing TiO/sub 2/ is an inherent problem and oven regulation for narrowband applications will be required. Small, inexpensive thermal jackets are available that will control the filter stability to a value equal to, or better than, that obtained with a filter utilizing aluminum cavities operating in a typical uncontrolled temperature environment.     

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.     

A Rectangular-Waveguide Filter Using Trapped-Mode Resonators

A two-resonator, narrow-band waveguide filter with a very wide stop band is described. Each resonator cavity has one side wall which is entirely open except for a bifurcating E-plane septum. Energy in most modes tends to radiate freely out of the open end of each resonator to absorbing material; however, energy in the fundamental TE/sub 101/-mode is trapped in the resonator structures to give high-Q resonances such as are typical of conventional solid-wall resonators. Thus, a primary pass band is obtained similar to that of filters using conventional cavity resonators, but the many higher-order pass bands usually found in cavity-resonator filters are largely eliminated because the higher-order-mode cavity resonances are damped out. This type of filter attenuates unwanted signals mainly by reflection. For applications where a low-input VSWR is desired in the pass band, a bifurcated section of guide backed by absorbing material is also used in the input waveguide so as to tend to absorb the input energy at frequencies above that of the pass band.     

Precise Design of a Bandpass Filter Using High-Q Dielectric Ring Resonators

A precise design is presented for a bandpass filter constructed by placing TE/sub 01delta/ dielectric ring resonators coaxially in a TE/sub 01/ cutoff circular waveguide. On the basis of a rigorous analysis by the mode- matching technique, the interresonator coupling coefficients are determined accurately from the calculation of two resonant frequencies f/sub sh/ and f/sub op/ when the structurally symmetric plane is short- and open-circuited. For the TE/sub 01delta/ ring resonator,the resonant frequency f/sub 0/, the temperature coefficient tau/sub f/, the unloaded Q(Q/sub u/), and the other resonances are also calculated accurately in a similar way. From the calculations, the optimum dimensions are determined to obtain the maximum Q/sub u/, as F/sub r/ = f/sub r/ /f/sub 0/ is kept constant, where f/sub r/ is the next higher resonant frequency the ring resonator using low-loss ceramics (epsilon/sub r/ = 24.3, tan delta = 5 x 10/sup -5/) has Q/sub u/ = 16800 at 12 GHz and tau/sub f/ = 0.1+-0.5 ppm/° C, while the rod one has Q/sub u/ = 14700. A four-stage Chebyshev filter having ripple of 0.04 dB and equiripple bandwidth of 27.3 MHz at f/sub 0/ =11.958 GHz is fabricated using these resonator; the measured frequency responses agree well with theory. The insertion loss is 0.9 dB, which corresponds to Q/sub u/ = 9800.     

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.     

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.     

大介电常数覆铜箔铜基复合微波介质基板的研制

通过对可调节介电常数的填充材料、介质厚度均匀性、铜板处理工艺的研究与选择,研制开发出了介电常数为6.15、介质损耗因数为0.0015的铜基高频电路用覆铜板。     

一种微波介质谐振器复介电常数测试方法

介绍了一种简单的微波介质谐振腔的设计及性能参数的计算方法，给出了相对介电常数ε1、介质损耗tan δ的详细求解方程，为微波介质陶瓷性能参数的测量提供了一种简单而有效的方法。     

BSZN微波介质陶瓷介电常数的异常

研究了(Ba1-xSrx)(Zn1/3Nb2/3)O3(BSZN)微波介质陶瓷介电常数的非线性变化以及异常的原因。随着系统中Sr(1/3Nb2/3)O3的增多,介电常数的异常是由于氧八面体的畸变导致的相转变(对称性降低)及第二相的生成造成的。未发生相转变前,介电常数的增大可用电介质理论加以解释;发生相转变后,介电常数呈线性下降趋势,符合对数混合定律。     

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。     

On the Narrow-Band Microwave Filter Design Using a Dielectric Rod

A method is presented to design bandpass or bandstop filters in the microwave region. The procedure is based on the analysis of the discontinuity problem of a circular cylindrical dielectric rod centered in a rectangular waveguide. For some special relations between the frequency, the dielectric constant, and the radius of the rod, the reflection or the transmission coefficient becomes equal to zero. This relation gives the narrow-band filter. Experimental results for filter design with the help of plastic and porcelain rods are given.     

High Breakdown Field Dielectric Elastomer Actuators Using Encapsulated Polyaniline as High Dielectric Constant Filler

A novel method allowing rapid production of reliable composites with increased dielectric constant and high dielectric strength for dielectric elastomer actuators (DEA) is reported. The promising approach using composites of conductive particles and insulating polymers generally suffers from low breakdown fields when applied to DEA devices. The present publication shows how to overcome this deficiency by using conductive polyaniline (PANI) particles encapsulated into an insulating polymer shell prior to dispersion. PANI particles are encapsulated using miniemulsion polymerization (MP) of divinylbenzene (DVB). The encapsulation process is scaled up to approximately 20 g particles per batch. The resulting particles are used as high dielectric constant (?′) fillers. Composites in a polydimethylsiloxane (PDMS) matrix are prepared and the resulting films characterized by dielectric spectroscopy and tensile tests, and evaluated in electromechanical actuators. The composite films show a more than threefold increase in ?′, breakdown field strengths above 50 V μm^?1, and increased strain at break. These novel materials allow tuning the actuation strain or stress output and have potential as materials for energy harvesting.     

Design of Microwave Oscillators and Filters Using Transmission-Mode Dielectric Resonators Coupled to Microstrip Lines

A more detailed model for the transmission-mode dielectric resonator coupled between microstrip lines is given. Novel design approaches for parallel feedback oscillators and bandpass filters are discussed. For oscillators, the design mainly takes into account zero phase shift loop considerations, as in the classical low-frequency approach. Oscillators of this type may offer low phase noise. For filters, the spatial separation between dielectric resonators favors multipole designs. Using the same microstrip layout, different shapes and bandwidths may be obtained by simple tuning.     

一种新型复合结构的四分之一波长带通滤波器

提出了一种基于共面波导(Coplanar Waveguide,CPW)和微带线复合结构的四分之一波长带通滤波器(Bandpass Filter,BPF)。该带通滤波器由两个终端开路的T形微带馈线结构和四个交叉耦合的四分之一波长CPW谐振器组成。通过仿真优化得到其特性曲线图,并分析比较了不同参数对其滤波性能的影响。仿真结果表明,该带通滤波器在其2.97～3.03 GHz的通带内的最小插损低于0.4dB,回波损耗大于30dB,同时其带外衰减都大于25dB。这种滤波器结构紧凑,尺寸小,性能好,可应用于很多微波系统中。