闭腔法测量微波介质材料参数的研究

采用TE01δ模闭腔法,推导了介电常数和介质损耗的计算公式.制作了4种介质谐振器,分析了支撑物的材质及高度、耦合的结构及强弱、金属腔材质对所制介质谐振器的谐振频率和品质因数Q值的影响.结果表明:较高的聚四氟乙烯支撑使介质谐振器有较高的有载Q值,弱的耦合使有载Q值非常接近无载Q值,高Q值的金属腔利于介质材料Q值的精确测量...     

回音壁模高Q蓝宝石谐振器研究与设计

采用径向+轴向模式匹配法完成了蓝宝石回音壁的模式分析,包括高次回音壁模式谐振频率的计算和电磁场分布,并研究了回音壁模谐振器的金属腔体设计等关键问题。制作的高Q蓝宝石谐振器在10.99GHz处,有载Q值达到了45000、插入损耗小于9dB。谐振器性能指标优越,非常适合应用于低相位噪声振荡器设计中。     

计算SIR同轴腔体物理参数的新方法

为有效减少滤波器设计周期,简化滤波器设计的过程,提出了一种根据谐振频率和无载品质因数Q值,精确计算阶梯阻抗谐振器同轴腔体谐振单元物理参数的新方法,并给出设计流程。使用HFSS仿真软件对该法进行仿真验证,相对于M.Makimoto等提出的计算方法,计算精度提高了1倍,计算的谐振频率误差小于1%,无载品质因数Q值误差小于8%。     

毫米波回音壁模介质谐振器

工作于TE、TM或混合模的微波介质谐振器,在毫米波段因尺寸小,Q值低,应用受到很大的限制.本文介绍的回音壁模介质谱振器,在毫米波段谐振器尺寸大,Q值高,且具有抑制寄生模的性能,特别适用于平面混合、单片集成电路.回音壁模介质谐振器在毫米波段将会有重要的应用前景.     

采用介质谐振器和Q值极高的新型微波晶体管振荡器

本文介绍采用介质谐振器作匹配电路和频率确定元件的单端口与双端口微波晶体管振荡器,其外部Q值比介质谐振器的无载Q值大得多。文中还指出,上述双端口场效应管振荡器的可能用途是作自振荡式混频器。     

微波谐振器无载品质因素的测量方法研究

提出了一种利用微波谐振器散射参数的幅度信息测量无载品质因素的方法.该方法认为在谐振点附近,耦合电路的参数和谐振器的参数相比可以忽略,因此采用简化的等效电路模型,利用谐振点附近的标量散射参数测量值来计算无载品质因素.为了消除散射参数曲线左右不对称所产生的影响,不采用散射曲线上独立的点来计算,而是采用带宽来计算.选取无载品质因素曲线平缓部分进行平均作为测量结果,测量精度接近临界点法.     

介质谐振器在微带电路中无载Q值的测量

本文提出了一种用测量与计算相结合的确定谐振器无载Q_u值的方法。此法尤其适用与微带线相耦合的介质谐振器的Q_u值的确定。只要测出与微带线相耦合的介质谐振器的谐振频率f_0,f_0。上的驻波比ρ和半功率点带宽△f_0.7,即可用本文给出的公式计算出介质谐振器的无载Q_u值和耦合系数β。实测结果表明所得的结果相对误差在5％以内。     

用谐振腔-截止波导技术测量介质谐振器的复介电常数

在TE01n模谐振腔的一个端面中央,开一圆孔,连接一根等直径、适当长度的截止波导,当截止波导中置入介质谐振器时,使含介质段对TE01模呈传输态。介质谐振器的前向波导段用于调节耦合强弱,足够长度的背向波导段则形成匹配电抗终端或置入金属场构成短路终端。这两种安排都能使置入介质谐振器前后的谐振腔产生相当大的谐振长度和Q因子的变化,从而能获得准确的介质谐振器无载Q因子和介电常数。在X频段对陶瓷谐振器进行测量,获得满意的结果。     

射频薄膜体声波谐振器的研制和分析

研制了一种采用氮化硅/二氧化硅/氮化硅复合膜作为支持薄膜的高Q薄膜体声波谐振器. 当采用单层氮化硅膜或二氧化硅膜作为谐振器的支持薄膜时,由于残余应力的作用,释放完的薄膜往往会出现褶皱的现象,极大地降低了薄膜体声波谐振器的Q值;上述复合膜结构有效地解决了这个问题. 采用直流磁控溅射法制备了氧化锌压电薄膜,X射线衍射结果表明制备的氧化锌薄膜具有很好的c轴择优取向,意味着氧化锌薄膜具有较好的压电性. S参数测试结果表明该薄膜体声波谐振器在0.4~2.6GHz的频率范围内具有3个明显的谐振模式,计算了这些谐振模式的串联谐振频率、并联谐振频率、有效机电耦合系数和Q值. 在这3个模式中,第3个谐波模式的工作频率约为2.4GHz,具有最高的Q值（约为500) ,可用来制备2.4GHz的低相噪射频振荡源.     

射频薄膜体声波谐振器的研制和分析

研制了一种采用氮化硅/二氧化硅/氮化硅复合膜作为支持薄膜的高Q薄膜体声波谐振器.当采用单层氮化硅膜或二氧化硅膜作为谐振器的支持薄膜时,由于残余应力的作用,释放完的薄膜往往会出现褶皱的现象,极大地降低了薄膜体声波谐振器的Q值;上述复合膜结构有效地解决了这个问题.采用直流磁控溅射法制备了氧化锌压电薄膜,X射线衍射结果表明制备的氧化锌薄膜具有很好的c轴择优取向,意味着氧化锌薄膜具有较好的压电性.S参数测试结果表明该薄膜体声波谐振器在0.4～2.6GHz的频率范围内具有3个明显的谐振模式,计算了这些谐振模式的串联谐振频率、并联谐振频率、有效机电耦合系数和Q值.在这3个模式中,第3个谐波模式的工作频率约为2.4GHz,具有最高的Q值(约为500),可用来制备2.4GHz的低相噪射频振荡源.     

Uncertainty analysis of the transmission-type measurement ofQ-factor

The transmission-type measurement of the Q-factor of a microwave resonator is analyzed with a goal of establishing uncertainty limits on the unloaded Q-factor. The three major sources of systematic errors which are discussed are: the instrumentation inaccuracy, the inequality of the input and output coupling coefficient, and the effect of coupling losses. It is shown that, for tightly coupled resonators, the uncertainty of the transmission-type method is significantly increased     

Precise measurements of the Q factor of dielectric resonators inthe transmission mode-accounting for noise, crosstalk, delay ofuncalibrated lines, coupling loss, and coupling reactance

Accurate measurements of the unloaded Q₀ factor of microwave resonators are necessary in many microwave applications. The most accurate values of Q₀ can be obtained by Q-circle fits from multifrequency S-parameter data. Practical measurement systems cause S-parameters of the resonators to be distorted from the circular ideal shape, rotated, and shifted from the origin resulting in errors in the Q-factor values. A novel Q-factor measurement method has been developed based on equations derived for resonators working in the transmission mode and fractional linear circle-fitting techniques. The transmission-mode Q-factor (TMQF) technique removes measurement effects of noise, noncalibrated measurement cables, connectors, coupling structures, crosstalk between the coupling loops, and impedance mismatch from the measurement data. The TMQF is especially useful in cryogenic measurements of high-temperature superconducting thin films and dielectrics since these measurements are typically done in the transmission mode and contain cables and connectors that are difficult to calibrate. The accuracy of the TMQF is better than 1% for practical measurement ranges and the method is applicable to a wide range of coupling. The range of Q factors measurable is from 10³ up to 10⁷     

微波Q值测量中的馈线相移消除方法

 提出了一种实用的测量微波谐振器无载品质因素的方法,在临界点法的基础上,消除了馈线引入的相移.该相移的出现会使谐振器等效阻抗曲线在Smith圆图中发生旋转,进而影响到测量结果.通过在Smith圆图中对测量的输入阻抗曲线进行旋转,根据寻找出的一个目标函数来判断合适的旋转角度,即为馈线引入的相移.对所提出的方法进行了数值模拟,并通过了一组实测数据做了验证.     

RF HBT oscillators with low-phase noise and high-power performance utilizing a (/spl lambda//4/spl plusmn//spl delta/) open-stubs resonator

This paper presents a new type of transmission-line resonator and its application to RF (microwave and millimeter-wave) heterojunction bipolar transistor (HBT) oscillators. The resonator is a parallel combination of two open stubs having length of /spl lambda//4/spl plusmn//spl delta/(/spl delta//spl Lt//spl lambda/), where /spl lambda/ is a wavelength at a resonant frequency. The most important feature of this resonator is that the coupling coefficient (/spl beta//sub C/) can be controlled by changing /spl delta/ while maintaining unloaded Q-factor (Q/sub u/) constant. Choosing a small value of /spl delta/ allows us to reduce /spl beta//sub C/ or equivalently to increase loaded Q-factor (Q/sub L/). Since coupling elements such as capacitors or electromagnetic gaps are not needed, /spl beta//sub C/ and Q/sub L/ can be precisely controlled based on mature lithography technology. This feature of the resonator proves useful in reducing phase noise and also in enhancing output power of microwave oscillators. The proposed resonator is applied to 18-GHz and 38-GHz HBT oscillators, leading to the phase noise of -96-dBc/Hz at 100-kHz offset with 10.3-dBm output power (18-GHz oscillator) and -104-dBc/Hz at 1-MHz offset with 11.9 dBm (38-GHz oscillator). These performances are comparable to or better than state-of-the-art values for GaAs- or InP-based planar-circuit fundamental-frequency oscillators at the same frequency bands.     

Characterization of high-Q resonators for microwave filterapplications

A one-port reflection technique is developed to measure the unloaded Q and external Q of a microwave resonator. The unique procedure of measuring unloaded Q is outlined in three easy steps. A sample chart is provided to further simplify the process. This method is so simple that even a scalar network analyzer is adequate for the measurement. In addition, a time-delay response around the resonator resonant frequency is also derived and presented. This theoretical result, combined with the advanced capability of modern vector network analyzers, has been proven to be very useful for characterization and tuning of the external Q of a resonator. All the results derived are verified by practical measurement. Finally, this technique is applied to the realization and tuning of a six-pole dielectric loaded cavity filter     

Study of whispering gallery modes in anisotropic single-crystaldielectric resonators

The Rayleigh-Ritz method and the finite element method nongenerating spurious solutions are employed for analysis of whispering gallery modes (WGMs) in cylindrical single-crystal anisotropic dielectric resonators. These methods allow accurate computation of the resonant frequencies, the Q-factors (depending on the dielectric and on the conductor losses), and the electromagnetic field distributions for all WGMs in the presence of additional elements like metal shields, MIC substrate, or supports. Different families of modes are studied both theoretically and experimentally. The mode coupling phenomenon is investigated. A WGM single-crystal quartz resonator is presented having an unloaded Q-factor greater than 30000 at about 100 GHz, including radiation and dielectric losses     

Microwave filters with improved spurious performance based onsandwiched conductor dielectric resonators

Microwave filters based on a novel resonator comprised of a sandwiched conductor dielectric resonator (SCDR) loaded in a cylindrical cavity are analyzed in this paper. The SCDR is a compact resonator that exhibits good spurious performance. Resonant frequencies of the lower order modes are analyzed, and mode charts, unloaded Q, slot coupling, and screw coupling graphs are presented. S-parameters are computed using the finite-difference time-domain (FDTD) method for one- and four-pole SCDR filters and compared with measured results. The measured spurious performance for the four-pole elliptic function filter shows a large improvement over conventional dielectric-resonator filters. The measured results agree closely with predicted values obtained using the FDTD method     

A Dielectric Resonator Method of Measuring Inductive Capacities in the Millimeter Range

A novel technique for the measurement of dielectric and magnetic properties of a homogeneous isotropic medium in the range of approximately 3 to 100 kmc is described. An accuracy of /l.chemc/ 1 per cent is possible in the determination of permittivity or permeability in those cases where the loss tangent is sulliciently small. The measuring structure is a resonator made up of a right circular cyndrical dielectric rod placed between two parallel conducting plates. For measurement of permittivity two or more resonant TE/sub onl/ mode frequencies are determined whereas for the measurement of permeability two or more resonant TM/sub onl/ mode frequencies are determined. The dielectric or magnetic properties are computed from the resonance frequencies, structure dimensions, and unloaded Q. Since the loss tangent is inversely proportional to the unloaded Q of the structure, the precision to which Q is measured determines the accuracy of the loss tangent.     

Radiation Losses of Planar Circuit Resonators and the R/Q Parameter (Short Papers)

The resonator parameter R/Q, the ratio of a shunt resistance to the unloaded Q, which might be termed a "mode-geometry" parameter, is a natural parameter for characterizing oscillation modes of planar-circuit resonators which are open circuited at the edges. These resonators are often excited by connection at the edge to a microstrip transmission line, and the appropriate shunt resistance is the equivalent resistance at resonance at these terminals for that mode. Losses in planar-circuit resonators include the ohmic (skin-effect and dielectric) losses of enclosed resonators plus a radiation-loss component. For a variety of planar resonators, the ohmic losses are easily calculated, but the radiation-loss determination is a difficult boundary-value problem. More specifically, the determination of either the unloaded Q or the radiation component of the unloaded Q is often readily accessible only through measurement. The knowledge of the R/Q parameter allows one, in effect, to replace the Q measurement with a shunt-resistance measurement, which is often more expedient to perform. Two simple planar-resonator configurations, the circular disk, and the square plate are studied. The radiation component of the Q is evaluated by using the measured shunt resistance and the R/Q parameter to calculate the total unloaded Q and thence the radiation component of the unloaded Q. A comparison is made between these results and those obtained from direct Q measurements.