Ferroelectric Tuning of Planar and Bulk Microwave Devices

Benefits of ferroelectric component applications at microwaves is discussed. Experience recently gained in the high-temperature film-production technology has been used for obtaining high-quality ferroelectric tunable components. The disk made from bulk SrTiO₃ single crystal covered with double-sided YBa₂Cu₃Y₇ films was used as a high-quality TM₀₁₀ mode tunable resonator. Planar structures containing thin film ferroelectric layers: planar capacitor, sandwich capacitor, coplanar line, and fin line have been studied. Modeling dielectric response of low-temperature incipient ferroelectrics (SrTiO₃, KTaO₃) has been applied for simulation of tunable planar structures. The quality factor of a tunable component (QFCT) is suggested to characterize the validity of the component for practical applications. The high-quality planar capacitors are pioneered for the applications. The wide frequency band fin line phase shifter has been studied and simulated. The prospects for applications of ferroelectric planar structures at room temperature is discussed.     

Reproduction of the Microwave Power Measurement Scale

Possible changes in the scheme for checking means of measuring microwave power by legalizing the concept of reproduction of the measurement scale, the introduction of which is considered as a stimulus to a more rigorous formulation of a method of extending the range of measured values of a quantity, is analyzed.     

Tuning Optimization for Second-Order Dynamic Filters for Random Signal Spectral Analysis

Initial formulas are derived for the spectral window of a narrow-band second-order dynamic filter and for the relative dispersion of the estimator for the spectral power density as measured by the correlation filter method, together with the general expression for the optimum tuning law for the filter damping coefficient for linear variation in the central frequency within the analysis band.     

适用于微机电系统的自适应红外探测器的可调谐滤光器设计与开发

微机电系统与高品质红外探测技术联合运用为国防、商业、通信、生物医学检测及环境监测等许多应用领域面临的一系列具有挑战性的问题提供了唯一可行的解决方案．可调谐法布里．玻罗滤光片是适用于微机电系统的红外探测器的核心部件．滤光片的结构设计和关键结构件的材料对于滤光片的性能和整个装置的完善性有重要影响．阐述了利用有限元建模进行法布里-玻罗滤光片机械设计和分析的方法．报告了滤光片的结构材料——用低温等离子增强化学沉积法制造的氮化硅的结构表征和机械性能测定方法和结果．最后展示了一些所制作的滤光片阵列．     

微波高功率对生长金刚石膜影响的研究

在实验室自制的10 kW微波等离子体化学气相沉积装置中, 系统分析提高功率对生长金刚石膜的影响。利用等离子体发射光谱诊断分析高功率微波等离子体放电环境的特征, 同时采用扫描电镜及Raman光谱对不同功率条件下获得的金刚石膜的形貌和质量进行表征。结果表明:微波功率的提高可以获得面积更大的强场区域, 为金刚石的大面积均匀成膜提供了有利条件;同时提高微波功率可以产生更高的电子密度, 激发更多的活性氢原子和有利于金刚石生长的含碳基团;在气压为15 kPa, H₂/CH₄流量比为200∶6 mL/min的条件下, 当功率由4000上升到5000 W时, 金刚石膜的质量明显得到提高;当功率升高到5500 W时, 金刚石质量开始下降, 出现孪晶;但在升高功率的过程中, 晶粒尺寸增大的趋势没有改变。因此, 提高微波功率易于活性氢原子的产生并可更为充分的活化含碳大分子基团;在本实验条件下, 当微波功率为5000 W时, 所制备的金刚石膜可具有较高的质量。     

Nonresonant Microwave Absorption in Bi2212 Single Crystal: Second Peak and Microwave Power Dependence

Nonresonant microwave absorption (NMA) measurements were carried out at liquid-nitrogen temperature on a high quality Bi2212 single crystal, as a function of microwave power in three mutual orientations of crystal ab plane, dc field (H_dc), and microwave magnetic field (H_w). NMA line shapes in Bi2212 crystal are complicated with a narrow peak (P₁ peak) located near zero field, followed by a much broader second peak (P₂ peak) in the particular orientations. More excitingly, we show that the P₂ peak qualitatively evolves as a function of microwave power in the orientation of H_dc ab plane, plane, and H_dc H_w. In this configuration, as the microwave power is progressively increased, the broad P₂ peak first gets smeared off and then a multiple peak structure appears, which develops into another narrower second peak (P_s-peak) at high enough microwave powers. In the orientation of plane, H_w ab plane, and H_dc H_w, we report for the first time the appearance and disappearance of a new second peak (P₂-like peak) as a function of microwave power.     

BPF小型化超导滤波器的研究与设计

本文对阶梯阻抗线微带谐振器（SIR）进行了研究，基于一般SIR模型设计了一个类SIR谐振器。由该谐振器构建的BPF不仅可使微带线BPF的尺寸小型化，而且可以控制微带线BPF寄生响应的位置。该谐振器更容易进行细微的调节与优化。利用所提出的谐振器结构设计了一个具有准椭圆函数响应特性的4阶超导带通滤波器，用全波分析软件进行了仿真与优化，并对所设计的超导滤波器进行了测试，结果表明，实际测试结果与理论响应符合良好。     

基于里德堡原子的微波功率精密测量

提出一种基于里德堡原子量子相干效应的功率测量新方法。将装有铷蒸气的低电磁扰动原子气室置于特定的导波系统中,基于里德堡原子量子相干效应将对导波电场测量转化为对原子吸收光谱的探测,利用功率和导波电场的解析量化关系,实现一种全新的可溯源至普朗克常数的微波功率测量。在10.22GHz频率处与传统功率测量进行比较,-40dBm至-20dBm的功率范围内两者平均偏差为0.08dB(1.86%)。这种全新的微波功率量子测量方法具有灵敏度高、动态范围大、测量不确定度小等优势,有望形成新一代可直接溯源至国际单位制(SI)的微波功率基准。     

几种高功率微波介质窗材料的研究综述

高功率微波介质窗的击穿问题已成为高功率微波武器发展的一个技术瓶颈,选择适当的介质材料、提高窗的抗击穿能力是解决此问题的一条重要途径.总结了国内外主要研究机构使用的高功率微波介质窗材料类型及特性,对各自优缺点进行比较分析,并给出了分析结论.     

Numerical Model of the Microwave Properties of Superconducting Resonators and Transmission Lines

We propose a model for microwave power transmission in superconducting lines and resonators. The correct current density incorporating the critical current density is used. A numerical self-consistent method is suggested to calculate different transport quantities, such as the surface resistance and the quality factor as function of both temperature and magnetic field. The effect of the strength of pinning on the transport properties is studied, as well. Some of these results are compared with experiment.     

Peculiarities of Pinning and Microwave Absorption Hysteresis in Thin Superconducting Films

The results of experimental and theoretical studies of the hysteretic microwave absorption (MWA) in the superconducting Bi₂Sr₂CaCu₂O₈ thin films are presented. It has been found experimentally that the hysteresis loop manifests some unusual features such as the non-monotone hysteresis variation and the change of a hysteresis sign. We have shown that such unusual behavior is due to the special nature of the bulk pinning in a superconducting film with a thickness comparable with the field penetration depth. The theoretical model of the MWA hysteresis has been developed taking into account the inhomogeneous distribution of centers with different symmetry of a pinning potential and their variation with the magnetic field value.     

微波功率对a-C:F薄膜结构和光学性质的影响

用苯 (C6H6)和四氟甲烷 (CF4 )混合气体作源气体 ,用微波电子回旋共振等离子体化学气相沉积技术制备了含氟非晶碳膜 (a C :F)。着重讨论了输入的微波功率对成膜结构和性质的影响。我们对沉积的膜作了膜厚、扫描电子显微表面形貌 (SEM)、紫外 -可见光透射谱 (UV -VIS)、傅立叶红外变换 (FTIR)等的测量。结果表明随着微波功率的增加沉积速率一直在上升 ;同时膜中缺陷增多 ;从FTIR的结果我们发现膜中主要以C -F、CF2 和F -芳基成键 ;通过UV -VIS吸收谱的测量的结果我们求出了折射率和光学带隙 ;并且将光学带隙和膜中的sp2 碳浓度建立关系     

Modulated Structural Characteristics and Microwave Properties of Spray Pyrolyzed Superconducting BCSCO Films

Low-cost–based high-T _c superconducting thin film of Bismuth Strontium Calcium Cuprate on yittriya stabilized zirconia (YSZ) using spray pyrolysis deposition technique from nitrate precursors followed by rapid annealing at temperatures between 830 and 840°C in air and in O₂ is described. The films are highly oriented with the c-axis parallel to the plane of the substrate. Some satellite reflections that occur due to the modulation along the crystal lattice (parallel to c-axis) are observed. The prominent X-ray diffraction lines can be fitted to a tetragonal structure. A number of satellite X-ray reflections lines are observed which suggest the existence of modulation. These lines have been fitted in a superspace group with a = 3.832 Å and c = 48.826 Å indicating the existence of superposed modulated structure. Substrates (Al₂O₃, LiNbO₃, Si₃N₄, Si) other than YSZ could not produce superconducting films due to the diffusion of metal ions in the film causing poisoning effect in superconducting properties. Resistivity measurements indicate superconducting onset at 92 K and zero resistance at 77 K. Microwave induced dc voltage (V) measurements as a function of microwave power (mW) were carried out at different temperatures down to 65 K for different annealing temperatures. It is noted that the slope of the line (V vs. mW) are dependent on ramping of the processing temperatures. The decrease of slope suggested that weak-links between the superconducting grains are decreased as the ramping of the processing temperature is decreased keeping the ramping time constant. The interactions between film and the substrate are qualitatively discussed.     

有源模拟滤波器的MATLAB辅助设计方法

在简要概述传统有源模拟滤波器设计方法的同时给出利用MATLAB进行有源模拟滤波器设计的方法,通过对有源模拟滤波器两种设计方法关键步骤的比较,给出了MATLAB能有效地简化有源模拟滤波器设计的结论。结合有源模拟滤波器的特性,给出了零极点分配原则和级联原则;同时介绍了如何用MATLAB给出滤波器总体和局部幅/相频特性,为滤波器调试提供了参考。通过设计实例,验证了本文提出的设计方案的便捷性、直观性、可行性。     

微波功率器件及其材料的发展和应用前景

介绍了微波功率器件的发展和前景,对HBT,MESFET和HEMT微波功率器件材料的特点和选取,以及器件的特性和设计做了分类说明.着重介绍了SiGe合金、InPSiC、GaN等新型微波功率器件材料.并对目前各种器件的最新进展和我国微波功率器件的研制现状及与国外的差距做了概述与展望.     

Bicriterial Design of Digital Filters

A problem of technical interest is the solution of approximation problems which make a tradeoff between the L ₂ norm and the L norm error criteria. This problem is investigated in the framework of filter design with respect to two conflicting optimality goals. The particular interest in L ₂-L norm compromise filters has been raised by a paper of Adams (IEEE Trans. on Circuits and Systems vol. 39, pp. 376–388, 1991), who suggested to compute such FIR filters by solution of certain constrained L ₂ approximation problems which require a proper choice of weights. It is shown in this paper that bicriterial filter design problems can be approached by classical methods from multicriteria optimization and that especially reference point approximation with the ideal point as reference point is a suitable tool to deal with Adams' problem. Solutions from this latter approach do especially not depend on the choice of weights and yield the best possible compromise filters with respect to a prescribed measure. The resulting optimization problems can be solved with (semi-infinite) programming methods having proven convergence under standard assumptions. Examples of L ₂-L norm compromise designs of a linear-phase FIR and an IIR filter are presented.     

同轴腔高功率多注速调管注-波互作用系统的模拟设计

以同轴腔高功率多注速调管为研究对象,以大信号程序KLY及PIC粒子模拟软件对其多电子注-波互作用系统开展了一维初始设计、二维等效设计及全三维模拟设计.通过采用二次谐波腔技术及参数优化,使同轴腔注-波互作用系统达到了70％以上的计算效率.与传统长漂移管方案注-波互作用系统相比,二次谐波腔方案不仅可以获得较高的注-波互作用效率,并且其系统长度可比传统方案缩短35％,有利于器件小型化.文中给出了以单通道圆柱腔代替多通道同轴腔的注-波互作用系统二维等效快速计算方法,与一维及三维计算结果的对比表明,这种方法具有较高的计算精度.     

短稳标准高Q值超导腔的研究

针对频率标准用超导腔的设计,通过理论分析及编程计算得到了影响微波腔指标的参数,并对不同温度下微波腔的品质因数（Q值）进行计算得到了温度变化曲线,通过此曲线可以确定达到指标所需要的温度。所设计的微波腔参数为：工作模式为TM₀₁₀模式,直径D为60mm,高度l为50mm,频率为4.4GHz,Q值在液氦温度4.2K时达到3.9×10⁷,在减压降温到2K时达到1.9×10⁹,实验结果与计算结果吻合。     

On the Power Handling Properties of High Temperature Superconducting Microwave Contiguous Duplexer

The power handling properties of a high temperature superconducting (HTS) microwave contiguous duplexer are measured in this letter. The HTS contiguous duplexer was fabricated using YBa₂Cu₃O₇ (YBCO) thin films on a 0.5-mm-thick LaA1O₃ substrate, operation frequencies of which are centered at 3.25 GHz and 3.75 GHz with 500-MHz-wide channels. The tested frequency response of power handling property of the HTS contiguous duplexer shows that there is a decreased power handling property on the crossover region; however, this microwave nonlinearity does not affect the engineering application of HTS contiguous duplexers and multiplexers.     

单层及双层手性吸波涂料的计算机辅助设计

本文给出了计算涂料型手性吸波材料反射性能的公式，结合实例分别讨论了手性参数的实部和虚部对手性吸波材料性能的影响。数值分析结果表明，选择适当的手性参数，手性吸波材料和普通材料相比性能可有所提高。通过改变手性在数的虚部能改变单层涂料的工作频带；对双层手性吸波材料来讲，手性参数的实部不但影响材料的吸波性能，也影响材料的工作频率，虚部对材料的性能几乎没什么影响。