TEM模式同轴谐振腔低气压放电蒙特卡罗仿真和实验研究

随着无线通信系统高频小型化的发展趋势,对微波滤波器设计提出更为严苛的要求。其中功率容量作为衡量滤波器性能的重要指标,在滤波器尺寸不断缩小的情形下面临严峻的挑战。谐振器作为滤波器基本组成单元,对单一谐振器的功率容量准确预测十分重要。本文针对工作频率在2.6 GHz的TEM模式同轴谐振器,将电容加载的耦合结构近似为平行平板结构,利用单粒子蒙特卡罗方法仿真获得同轴谐振器临界击穿电场,实现了对该结构同轴谐振腔的低气压放电功率阈值仿真预测。对所设计同轴谐振腔开展低气压放电实验研究,获得了100～1000 Pa气压范围内击穿功率阈值随气压的变化关系实验曲线,并验证了单粒子蒙特卡罗仿真预测方法的准确性。     

微带与腔体梳状线可调带通滤波器设计

主要介绍梳状线可调滤波器设计的两种结构形式,平面结构采用微带线,使用ADS软件仿真设计;三维结构采用同轴腔体,使用HFSS软件仿真设计。梳状线滤波器因其具有结构紧凑的特性,在小型化滤波器的应用场合中较为常见,就两种以梳状线滤波器的工作原理,采用不同的传输线形式进行设计,并进行成本,性能等方面的对比。     

阶跃阻抗同轴介质滤波器的设计

提出一种新型阶跃阻抗同轴滤波器的设计方案,并以小灵通射频前端滤波器为例,介绍了整个设计流程.与均匀阻抗同轴滤波器相比,阶跃阻抗同轴滤波器能够减小谐振波长,从而减小滤波器的尺寸.同时在同轴内导体表面开槽,能进一步减小滤波器的尺寸.     

四合一天线合路器的控制与实现

介绍了一种基于FPGA控制的四合一天线合路器，文中介绍了该合路器的硬件结构，软件控制算法以及工程上的实现方法。     

高介电常数微波介质陶瓷的研制及其同轴型滤波器的仿真

本文研制了一种由双镧系元素组成的BaO-Ln2O3-TiO2(BLT)系高介电常数、低损耗材料,并以该材料为基础,设计并研究了其独石型同轴滤波器。滤波器采用新颖的凹槽式电感耦合和一端金属面短路的λ/4结构。利用HFSS高频仿真软件对该滤波器的传输特性进行了仿真,表明其具有中心频率为1.83GHz、带宽43MHz、插入损耗小于0.5dB、带内纹波为1.5dB的优异的通带特     

双通带带通滤波器的分析与设计

基于方型环与开路线相结合的结构设计了一种新型微带双通带带通滤波器.该滤波器通过调节方型环与开路线的尺寸分别获得两个通带.经仿真优化,并制作了实物模型.测试结果表明该滤波器能够工作在2.365 GHz和4.465 GHz,插入损耗都小于3 dB.测量结果与仿真曲线一致性较好.该滤波器结构简单、设计方便、体积小、易于加工,便于与其它电路集成,可以广泛应用于射频前端.     

传输法模拟滤波器型输出回路的间隙阻抗频率特性

利用传输法把滤波器型输出回路等效为双端口微波网络问题,通过理论分析,数值模拟和冷测实验证明了S21平方后的曲线能定性反映滤波器型输出回路的间隙阻抗频率特性.从而在仿真设计阶段,可将S21设为优化目标,利用三维电磁仿真软件的参数优化功能实现精确设计滤波器结构,比相位法,场分析法更加快捷准确.传输法同样适用于矢量网络分析仪冷测滤波器的实验,可消除系统拆装及波导元件引起的误差,使测量更加方便准确.     

基于蚁群算法的光学膜系初始结构优化设计

本文在分析和研究蚁群算法原理、算法实现过程的基础上,针对多膜料设计,以1200～1600nm波段内带通滤波器、1200～1600nm波段内截止滤波器、600～1000nm波段内截止滤波器和400～800nm波段内截止滤波器等4个滤波器实例为优化对象,以理论反射率和实际反射率之差最小为目标函数,采用蚁群算法和MATLAB语言编制了膜系初始结构优化设计的仿真计算程序,计算机仿真结果准确,证明了蚁群算法应用于膜系设计的可行性.     

多项滤波器算法在水声信号处理中的研究和仿真

主要对多项滤波器算法在水声信号处理中的应用进行了理论分析和算法仿真.为实现抽样率转换而产生的多项滤波器算法,通过对信号进行抽取和插值相结合的方法来控制信号的抽样率.对抽取-插值滤波器依照减少乘法运算次数的原则进行结构上的简化,并进行数学推导,最终得到多项滤波器的结构框图和数学表达式.运用MATLAB对多项滤波器算法进行仿真,并对仿真结果作了理论分析.     

基于SIR的同轴腔体带通滤波器设计

基于阶跃阻抗谐振器SIR(stepped impedance resonators)的基本原理,采用λg/4型SIR作为基本谐振单元,设计了一款小型化同轴腔体带通滤波器.仿真结果显示,相比实际长度λg/4该滤波器尺寸压缩了56.7%,通带内回波损耗小于-17.5 dB,插入损耗小于0.1 dB,带外抑制度达到了-38.8 dB,满足了现代通信系统对滤波器小型化、低插入损耗、高选择性的要求,能够广泛应用于现代移动通信系统.     

An electromagnetic analysis of a coaxial cavity cell

An electromagnetic analysis of a coaxially-excited coaxial cavity is presented. Equations are derived for the fields inside the cavity, the currents on the conducting walls, and for the cavity admittance. An accurate approximate method for calculating the losses in the cavity walls and the effect on the admittance is also reported. Experimental results are presented which demonstrate the accuracy of the theory. This work represents the first step in the development of a technique to employ the coaxially excited coaxial cavity as a cell for the measurement of the permittivity of homogeneous materials over a wide frequency range     

L3型二维平板光子晶体微腔品质因数优化

二维平板光子晶体微腔在垂直于平板方向上存在辐射损耗,使得微腔品质因数不够大,限制了其应用。结合光子晶体微腔损耗的傅里叶分析,采用调整腔模空间分布的方法,减少了波矢在辐射泄漏区域的分布,进而降低了腔损耗,实现了微腔品质因数的优化。针对L3型二维光晶体微腔的结构设计,对具体的L3型光子晶体微腔优化进行了数值仿真,仿真结果表明微腔品质因数得到了极大的提高,验证了光子晶体微腔品质因数优化方法的有效性。     

基于仿真分析的单点系泊液滑环结构设计

液滑环是海洋油气开发用单点系泊系统的关键部件,是亟待实现国产化的装置之一。采用流场仿真方法,对滑环型腔内流场进行详细分析,研究了速度和压力分布,结合滑环对流体冲击力和泥沙沉积等要求,给出某液滑环国产化研发项目样机的腔体形状的优化方案;同时,基于有限元仿真分析方法对液滑环进行了强度校核。为液滑环的腔体设计、构件设计提供参考。      

Field attenuation as the underlying principle of cryo current comparators

This paper describes both theoretical and experimental investigations of the error behaviour of cryo current comparators (CCC) as a function of the geometric parameters of the superconducting shields. The basis of our calculations has been the attenuation of magnetic fields by a superconducting coaxial cavity. The theoretical results agree with experiments which have been performed on a special test configuration of a CCC. Its main feature is a toroidal shield made from mercury with an elongated gap region forming the coaxial cavity.The results obtained are applicable to all types of CCCs. We found that the superconducting coaxial cavity behaves like a filter which transmits only the useful signal containing information about the net current linkage. All other fields contributing to the error of the comparator are attenuated exponentially.     

Structure Design and Optimization of Deep Cavity Rollers of Rotary Steering Spindle System

The center shaft of rotary steering spindle system is bendable under bias force. A severe partial load effect occurs among rollers, the inside and outside circles of the first cantilever bearing. Simulation analysis was conducted by loading boundary condition of the spindle under bias force. Furthermore, three different types of deep cavity rollers, which were cylindrical, conical, and spherical, respectively, were analyzed by finite element method. The effects of deep cavity angles, radius, and offset on mechanical properties of bearing were studied. The data obtained by simulation analysis were trained and predicted by Back Propagation (BP) neural network, and then the BP neural network model was incorporated into fmincon function. Thereby, structure optimization of rollers was established based on BP neural network model and fmincon function. The results show that structure of the conical deep cavity roller gets optimal mechanical performance. After being optimized, maximum stress of edge region and elliptical area decreases, respectively, by 22 and 17% than before, indicating that structure optimization method of the neural network and fmincon function can be used in optimization of deep cavity rollers. This method can quickly search for the optimal solution with sufficient engineering accuracy, ease of use, and adaptability.     

R134a汽车空调及整车降温性能仿真优化分析

本文通过KULI仿真软件搭建整车降温模型,计算并分析了中间换热器(又称同轴管,IHX)、后出风吹面装置以及乘员舱衣帽架对乘员舱降温性能的影响,对比了其单一装置及其组合方案对整车降温性能的影响。分析结果显示当取消单一功能配置时,衣帽架对乘员舱降温性能影响较大,平均温度升高2.2~2.4℃;后吹面装置次之,平均温度升高0.6~0.8℃;同轴管的影响最小,平均温度升高0.2~0.4℃。而且衣帽架单一装置对乘员舱降温性能的影响大于同轴管和后出风吹面装置组合对乘员舱降温的影响。通过仿真计算为整车及后续车辆开发提供了一定的理论依据及优化方案。     

Two Methods for Measuring High Permittivity at Microwave Frequencies

Permittivity is measured by impedance measurement on thin cylindrical samples placed in an ordinary rectangular waveguide and in a cavity formed by an ordinary coaxial transmission line. The first method does not depend on resonance and is characterized by a rather high accuracy. The second, more conventional method, is used in conjunction with the first for study of dc bias dependence of the permittivity.     

Experimental study of a perforated coaxial exciter of high-order modes in a barrel-shaped cavity

A method proposed previously [1], according to which high-order modes in a barrel-shaped cavity are selectively excited using a coaxial waveguide with a double periodic perforation of the wall, has been experimentally realized. A rotating H₁₁ waveguide mode has been converted into a rotating H₅₃₁ eigenmode with a conversion efficiency of about 98%.     

某拖拉机驾驶室声学特性分析与改进

为了降低拖拉机驾驶室内中高频噪声,建立基于统计能量分析(SEA)方法的驾驶室内噪声预测模型。通过理论计算和试验方法确定模型的基本参数和激励输入,通过仿真与试验对比验证了SEA模型的准确性。最后对驾驶室内声腔的功率输入分析,得到对驾驶室内噪声贡献较大的板件子系统,据此提出有针对性的声学包装改进方案,仿真结果表明该声学包装设计方案可以有效降低驾驶室内中高频噪声,总声压级降低1.87 d B(A),为拖拉机驾驶室内噪声控制及声学包装优化提供有效依据。     

Permeability evaluation of ferrite pastes, epoxies, and substratesover a wide range of frequencies

Two accurate methods for determining the magnetic constants of ferrite pastes, epoxies, and substrates are proposed. The first method is used for low-to-mid frequencies (DC-100 MHz) and is based on current images. The permeability is calculated from measurements of the inductance of thick-film spiral inductors printed on the magnetic material under investigation. The second technique is a frequency-domain coaxial cavity method and is used for the mid-to-high frequency range (50 MHz-2 GHz). The complex permeability is calculated using this method