镀铝玻纤复合材料电磁屏蔽性能探讨

以镀金属铝玻璃纤维为导电填料,填充热固性酚醛树脂制备出电磁屏蔽复合材料。通过测试和分析发现,一定长度下以镀铝玻纤作为导电填料仍然具有阈值性质,且填充量大于40wt%后,材料的屏蔽效能开始保持稳定。同时,用经典的同轴线模型公式估算了相同体积电阻下材料的屏蔽效能,发现其值与实测值具有一定偏差。最后,分析了偏差的原因,指出材料自身结构亦是获得较高屏蔽效能的重要手段之一。     

Artificial Magnetic Conductor Based on a Composite Material with Anisotropic Dielectric Permittivity and Its Application as a Small Screen

Journal of Communications Technology and Electronics - The structure of an artificial magnetic conductor (AMC) of alternating dielectric layers with high and low permittivity is presented. By...     

Radio Absorber Based on an Artificial Magnetic Conductor and Resistive Film

Journal of Communications Technology and Electronics - Analytical expressions are presented for the frequency-angular dependences of the reflection coefficient from a radio absorber (RP) based on a...     

Tuning the Operating Band of an Artificial Magnetic Conductor

Journal of Communications Technology and Electronics - Approximate formulas for calculating the coefficient of reflection from an artificial magnetic conductor (AMC) based on a capacitive lattice...     

考场手机屏蔽器电磁辐射的研究

目前考场普遍使用手机屏蔽器,许多家长产生了手机屏蔽器对考生电磁辐射影响的忧虑,文中对高考考场普遍使用的手机屏蔽器进行了分析研究,利用时域有限差分法计算了其在考场内的场强分布,进行了实地测量,两者结果符合的比较好,并且依据国家标准对该手机屏蔽器的电磁辐射影响给出了定量分析。     

电磁辐射防护服屏蔽效能测量系统的研制

建立了一套系统的测量方法和实验手段,对电磁辐射防护服的屏蔽效能进行测量。通过分析目前电磁辐射防护服的国内外标准,对电磁防护服评价的频率范围、电磁辐射曝露限值、电磁屏蔽效能等级等评价指标给出建议,并对电磁辐射防护服屏蔽效能测量系统的构成和测量方法、测量系统中的天线类型和安放位置等进行了详细说明。     

Structure of an Artificial Magnetic Conductor with a High Angular Stability of Resonance Frequency

Journal of Communications Technology and Electronics - An artificial magnetic conductor based on a capacitive grating the period of which is greater than the distance between the grating and screen...     

Dual-Band Low-Profile Antenna Array Based on a Hybrid Metastructure with the Properties of an Artificial Magnetic Conductor and Partially Reflective Surface

Journal of Communications Technology and Electronics - The configuration of a dual-band antenna array with a frequency ratio of 1 : 3 based on integration with metastructures having the properties...     

Studying the Thermodynamic Properties of Composite Magnetic Material Based on Anodic Alumina

Russian Microelectronics - In this paper we study the thermodynamic, morphological, structural, and chemical properties of a composite material consisting of nickel nanowires (NWs)...     

镀Ni-Cu-La-B玻璃纤维对电磁屏蔽复合涂料性能的影响

以一种新型镀Ni-Cu-La-B玻璃纤维与片状镍粉为复合填料,以丙烯酸树脂作为粘结剂,研制出了一种新型镀Ni-Cu-La-B玻璃纤维/片状镍粉/丙烯酸树脂电磁波屏蔽复合涂料,并研究了其导电性能和电磁波屏蔽性能。结果表明,添加6 wt%的镀Ni-Cu-La-B玻璃纤维能显著改善涂层的电磁性能,膜厚300μm,涂层电阻率为0.68Ω·cm,涂层屏蔽效能在0.3～1 000 MHz频段内为47.78～64.28 dB。为研制低成本电磁波屏蔽涂料提供了一种新的思路和方法。     

基于空间场屏蔽效能测试方法研究

基于空间电磁场屏蔽效能测试中,目前存在着各种测试标准,虽然每种方法都能获得实验数据,但是不同测试方法下的实验数据差异性很大,不具有可比性。针对以上问题,该文对各种方法的选用、原理以及优缺点展开详细的研究和分析,并对基于空间电磁场屏蔽效能测试方法标准的统一性和规范化做了相应的建议和尝试,来优化和控制屏蔽部件、屏蔽材料和屏蔽实体的屏蔽效能测试,使测试标准更加符合实际测试和生产实践。     

Excitation of an External Terminated Longitudinal Conductor on a Rocket by a Transverse Electromagnetic Field

A single conductor of arbitrary length is placed close to the surface of a conducting cylinder parallel to its axis. Impedances are connected between the ends of the cable and the cylinder. An incident monochromatic plane electromagnetic wave propagates in the longitudinal direction and is thus polarized in a transverse plane with respect to the axes of the external conductor and the cylinder. The component of the electric field tangent to the terminating impedance excites the circuit. The objective is to derive formulas for the currents in these impedances. The transverse dimensions of the conductor satisfy the inequalities a1 ? a2 ? ?, where a1 is the radius of the external conductor and a2 is the radius of the cylinder. It is assumed that the distance d between adjacent points on the conductor and the rocket is small compared with the wavelength.     

基于MRTD的天线电磁辐射分析

系统地研究了时域多分辨（MRTD）算法,并利用该算法计算天线的电磁辐射,验证与其他算法比较下所具有的优越性,推导出采用具有紧支撑特性的Daubechies小波作为展开基的MRTD算法的计算公式,分析其色散特性和吸收边界条件,通过模型分析圆柱形单极天线的电磁辐射,仿真出该天线的一系列电参数值,经过优化可以得出比较理想的结果。结果表明MRTD具有良好的色散特性和精度,同时还具有计算速度快、存储空间少和内存使用量小等优点,有效地弥补了其他计算机电磁算法的不足。     

材料磁性对电磁理论中菲涅尔公式的影响

本文考虑材料的磁性,利用电磁场的边值关系研究磁导率对菲涅尔公式的修正。文中利用所定义的介质界面矢量将电磁场量正交分解,统一处理垂直和平行于入射面的场分量关系,提供推导菲涅尔公式的另外方法,并对结果进行深入讨论。结果表明,材料磁性对菲涅尔公式的修正可以由两种材料的相对磁导率之比描述。     

基于矢量有限元法的热沉结构电磁辐射研究

 高频、高功率芯片工作时会产生大量的热,热沉可以有效地帮助芯片散热.然而在高频环境下,热沉往往成为主要的电磁辐射源,降低了整个系统的电磁兼容能力,所以有必要对热沉的电磁辐射特性进行研究.本文采用矢量有限元法,从不同的接地方式、散热鳍片数目及厚度变化、鳍片高度变化几个方面分析了热沉的电磁辐射特性,提出了影响谐振频率的关键因素,并从电磁兼容角度提出了热沉设计的注意事项.数值仿真表明,合理的选择接地方式可以有效地提高谐振频率,降低电磁能量辐射;散热鳍片的数目和厚度变化对于谐振频率和电磁辐射没有明显的影响,然而鳍片的高度对于电磁辐射能量影响显著.     

组合导体目标电磁特性的快速多极算法计算

用快速多极算法分析具有任意线、面、体组合的电大尺寸理想导体目标的电磁散射和辐射特性.统一采用RWG基函数对线、面、体导体上的电流进行展开;使用了新的设置基函数和未知量的方法来处理任意的线-面,面-面连接问题;并使用多层快速多极算法结合ILUT预处理算法加速求解过程.数值结果验证了本文方法的准确性和高效性.     

Planar Diffraction Analysis of Homogeneous and Longitudinally Inhomogeneous Gratings Based on Legendre Expansion of Electromagnetic Fields

Planar grating diffraction analysis based on Legendre expansion of electromagnetic fields is reported. In contrast to conventional RCWA in which the solution is obtained using state variables representation of the coupled wave amplitudes; here, the solution is expanded in terms of Legendre polynomials. This approach, without facing the problem of numerical instability and inevitable round off errors, yields well-behaved algebraic equations for deriving diffraction efficiencies, and can be employed for analysis of different types of gratings. Thanks to the recursive properties of Legendre polynomials, for longitudinally inhomogeneous gratings, wherein differential equations with non-constant coefficients are encountered, it can also be used to analyze the whole structure at one stroke. Although this is the only case for which the presented approach is efficient from both aspects of stability and computation load, the presented approach is applied to different test cases, and justified by comparison of the results to those obtained using previously reported methods. The method is general, and can handle many different cases like thick gratings, non-Bragg incidence, and cases in which higher diffracted orders or evanescent orders corresponding to real eigenvalues, have to be included in the solution of the Maxwell's equations. In deriving the formulation, a rigorous approach is followed     

基于小波矩量法的平面螺旋电感的电磁辐射研究

 平面电感实现了电感器件的小型化和片式化.当工作频率达到射频或微波段时,应考虑平面电感线圈的辐射和散射对其周围电路的影响.本文采用小波矩量法研究了PCB(printed circuit board)平面螺旋电感的电磁辐射特性.采用区间小波作为矩量法中的基函数和检验函数,计算了电感中的电流分布,给出了辐射方向图.与传统矩量法相比,小波矩量法可以使系数矩阵稀疏化,从而节省了计算机资源和计算时间.     

基于谐振腔体法的材料电磁参数测试

本文介绍了一种全新的分裂圆柱体谐振腔体,并且以聚四氟乙烯的测量为例,详细介绍了采用这种腔体完成介质材料测试的具体过程.此项方法具有精度高、操作简单的特点,最适合于衬底,薄膜,PCB等材料的测量,并且遵循IPC测试规范TM-650 2.5.5.13.     

基于物联网的电磁辐射监测系统的设计

本文将物联网技术应用于电磁辐射监测系统,设计了一种基于物联网的电磁辐射监测系统总体方案,在搭建了硬件平台的基础上设计实现了各软件模块。测试结果表明,该电磁辐射监测系统实现的功能包括电磁辐射水平监测、存储和管理监测数据、通过无线通讯设备向监测中心传输数据等,完全满足设计要求,可以用于创建中小型重点区域范围内电磁辐射监测网络。