矩形金属屏蔽壳中几种介质腔谐振频率的精确计算

本文采用本征函数匹配法分析了在矩表金属屏蔽壳中有多层介质基片填充，放置任意位置的圆柱，圆环及方形介质腔的谐振频率，计算了谐振频率随外壳尺寸，介质腔尺寸变化的几组曲线，经与实验数据及圆柱屏蔽壳情况值比较表明本文结果正确。     

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...     

有孔圆柱介质谐振频率的自动测试方法

从求解Maxwell方程本征值出发,采用MATLAB中PDE工具箱,借助可二维作图的开槽圆柱谐振器,计算出有孔圆柱介质谐振器的谐振频率。求解结果与矢量网络分析仪测量结果吻合,误差在千分之四以内。且该有限元法计算软件采用MATLAB编写,可方便地被调用于矢量网络分析仪的VEE测试软件中,较好解决有孔及变形圆柱介质谐振器的设计、测量和微调等问题,特别是矢量网络分析仪的快速自动测量中。     

耦合腔行波管中的切断匹配负载的设计和测量

介质谐振损耗腔用作耦合腔行波管切断处匹配负载，国内外已进入实用阶段，本文就此进行讨论，并给出了该介质腔谐振频率，介电常数，品质因素和损耗角的计算及测量方法，在研制一只Ｃ波段５０ｋＷ耦合的腔行波管中，理论与实则吻合，表明了本文理论分析和测量方法的有效性和可行性。     

二维光子晶体波导微腔传输特性的研究

用时域有限差分(FDTD)法和快速傅里叶变换(FFT)方法计算了二维正方格子光子晶体的点缺陷的谐振频率,研究了点缺陷的半径和背景材料折射率的变化对谐振频率的影响.研究结果表明,谐振归一化频率随点缺陷的半径或背景材料折射率增大而减小,当点缺陷半径增大到0.45r时,谐振中心归一化频率为0.336,波导微腔传输系数最大为9...     

基于连续谱束缚态的高Q太赫兹全介质超表面

为了研究基于连续谱束缚态(BIC)高品质因子Q谐振, 提出了由双空心硅圆柱体组成太赫兹全介质超表面。采用数值模拟方法对结构的透射光谱及电磁场图进行了分析, 并利用本征模分析的方法研究了超表面结构参数对BIC频率的影响, 给出了该BIC超表面在太赫兹大频率范围工作的参数设计方法。结果表明, 在3.0THz左右实现了一个可调高Q环偶极Fano谐振; 本征模式的分析计算结果与入射电磁波模式的分析计算结果对称性不匹配, 该超表面支持的是一个对称保护BIC。此研究为基于BIC的高Q超材料在超低阈值激光器件、非线性光学谐波产生及高灵敏度传感等领域的应用提供了理论参考。     

回旋速调管群聚腔研究

本文采用场匹配法对回旋速调管群聚腔进行了理论分析和数值模拟,讨论了两端开孔对腔谐振特性的影响及引入损耗介质层降低Q值方法,给出了一种工作频率为34GHz,工作模式为TE 01的回旋速调管低Q群聚腔的计算结果,结果表明,开孔大小明显影响腔内的谐振特性及驻波分布,损耗介质层的厚度增加将使群聚腔Q值迅速降低,选择适当的腔体结构,损耗介质及其厚度能有效地降低Q值,满足设计要求.     

一种求解微波介质谐振器复介电常数的方法

根据微波谐振系统中电场的波动方程,采用复频率和有耗导体的边界条件,导出以被测介质的复介电常数为本征值的微分和变分方程。使用MATLAB软件中的PDE工具箱,只要是能以二维形式作图表现的微波介质谐振器,都可以求解出其复介电常数,且与实验数据及不同方法计算的结果相吻合,该方法适用面广、计算精确、简洁方便。     

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。     

介质加载矩形谐振腔分析

利用导波系统中传输模的横向谐振法,导出了介质加载矩形谐振腔中分层介质区内谐振模的本征值方程,由此可精确地求解其谐振频率。     

瞬变等离子体中电磁波频率漂移特性研究

推导一维瞬变磁化等离子体的时域有限差分(FDTD)递推式,并以一维金属谐振腔作为计算模型,分析了瞬变等离子体中电磁波频率漂移特性。从理论分析出发,得到了一维瞬变等离子体对电磁波作用的解析解。通过选取相同的模型和参数,将FDTD数值解与解析解进行对比,验证了所用FDTD方法的准确性,在此基础上研究了瞬变等离子体中电磁波的频率漂移规律。     

基于矢量有限元法的谐振腔通用模拟器设计

开发了基于矢量有限元法的谐振腔通用计算模拟器。该模拟器包括前处理、有限元求解和后处理三部分。首先在前处理中进行三维实体建模和网格剖分,然后采用有限元方法生成矩阵并求解该矩阵,在后处理中计算谐振腔的任意本征频率,Q值及电磁场分布。通过分别对几种不同介质包括各向异性介质加载下的谐振腔进行仿真求解,并将计算结果与商业电磁仿真软件HFSS进行对比,验证了模拟器的可行性以及仿真谐振腔的通用性。     

Study of TE0 and TM0 modes in dielectricresonators by a finite difference time-domain method coupled with thediscrete Fourier transform

An application of a numerical method of finite differences in the time domain (FDTD) coupled with the discrete Fourier transform is presented to determine the resonant frequencies of the TE₀ and TM₀ modes of axially symmetric dielectric resonators closed in a cavity. The technique is conceptually and computationally simple, and it allows access at once to information on the entire modal spectrum by means of the fast Fourier transform (FFT) applied to the time series. The cylindrical cavity dielectrically loaded at the base and the resonant frequency of the TE_01δ mode are analyzed in two systems: a cylindrical cavity with a cylindrical dielectric resonator of variable radius, and the shielded dielectric resonator on a microstrip substrate. The results obtained are compared with the rigorous (exact) theoretical solutions and with experimental results     

Hybrid NEC/FDTD approach for analysing electrically short thin-wireantennas located in proximity of inhomogeneous scatterers

A new hybrid technique is presented which combines the method of moments with the finite difference time domain (FDTD) method to analyse electrically short, thin-wire antennas located in the vicinity of inhomogeneous dielectric bodies. The antennas are dealt with in the frequency domain using the NEC coder while the FDTD method is used to analyse the inhomogeneous part of the problem. The two sub-problems are combined by invoking the equivalence theorem     

The wave-equation FD-TD method for the efficient eigenvalueanalysis and S-matrix computation of waveguide structures

A modified finite-difference-time-domain (FDTD) formulation based on the direct discretization of the vector wave-equation is applied to the efficient analysis of hybrid-mode waveguiding structures. For both 3-D and 2-D waveguide eigenvalue problems, the formulation requires only one grid, and just the solution of three coupled equations is necessary. Numerical examples concerning the resonant frequencies for an inhomogeneously filled waveguide resonator as well as the fundamental- and higher-order-mode propagation factors for insulated image guides, shielded coupled dielectric guides, and lateral open dielectric ridge guides demonstrate the efficiency of the method. The theory is verified by comparison with results obtained by other methods     

平板介质的微波分裂腔法介电常数测试技术

为实现微波频段平板类介质材料的介电常数的无损测试,研究了分裂式圆柱形谐振腔测试方法。介绍了分裂式圆柱形谐振腔的电磁场分析理论,采用模式匹配技术实现了介质加载条件下腔内电磁场分布的精确求解,得到了腔体谐振频率与材料介电常数之间的准确关系。在理论分析的基础上,制作了空腔谐振频率为10 GHz的分裂式谐振腔,并与前期研制的闭式谐振腔进行对比测试,介电常数实部测量结果相对误差小于1%。与国外同类产品进行对比测试,介电常数实部结果基本一致,损耗角正切测量结果更接近于文献参考值。因此,微波分裂腔法能够实现平板介质板材的无损测量,具有准确度高,使用方便等突出优势,可在微波频段内实现介电常数为1～20,损耗角正切为1×10^-3～1×10^-5,板材厚度为0.1～2.0 mm的各类平板介质材料介电常数的准确测试。     

Measurements of Microwave Conductivity and Dielectric Constant by the Cavity Perturbation Method and Their Errors

The theory and technique of the cavity perturbation method for measuring the conductivity and dielectric constant of materials are reviewed. An analytical formula for calculating the errors of the conductivity and dielectric constant caused by the measured error in the resonant frequency and quality factor are derived. This formula can be used for both rectangular and cylindrical cavities. The results of measurements on silicon samples are presented to illustrate this analysis.     

气体激光器圆柱形微波激励谐振腔的微扰理论分析及其应用

导出了工作于ＴＭ０１０模的圆柱形微波等离子体腔中等离子体与腔谐振频率关系的精确解析式和微扰近似公式，比较结果表明：在微波激励低气压气体激光器中微扰理论可相当精确地分析微波等离子体对腔的扰动效应。给出了消除等离子体与管壳的扰动引起的腔失谐的方法，从而在气体激光器中成功地形成了稳定与均匀的微波等离子体和稳定的激光输出。用微扰理论使此腔又具有测量等离子体电子密度和管壳微波介电常数的功能     

Equivalent Resonant Cavity Model of Arbitrary Periodic Guided-Wave Structures and Its Application to Finite-Difference Frequency-Domain Algorithm

An equivalent resonant cavity model is proposed and developed for efficiently and accurately extracting the complex propagation constant of any arbitrary bounded and unbounded periodic guided-wave structures, which is known as a difficult eigenvalue problem with respect to a deterministic or S-parameter-based field solver. In this study, this problem is formulated as a standard eigenvalue one, which is made possible by effectively translating the transmission distance-related attenuation part of complex propagation constant into a time-dependent damping factor. This allows the development of an equivalent resonant cavity model to substitute or replace the periodic guided-wave model, leading to a complex frequency simulation model. As a result, the simulation time and storage requirement are then reduced significantly with this complex frequency approach. A finite-difference frequency-domain algorithm combined with this model is used to demonstrate the concept, and the properties of arbitrary complex closed/open periodic guided-wave structures are rigorously investigated. The proposed algorithm has been validated by both simulations and experiments