方孔金属线网屏两侧电磁场的精确表达式

利用层阻抗边界条件模拟方孔金属线网屏对电磁场的影响.推导出平面线网屏两侧谐变垂直电、磁偶极子的反射和透入电磁场精确解析表达式.应用圆柱波函数的球面波展开式和超几何函数理论,场分量中的Sommerfeld型积分表示为绝对、快速收敛的球面波函数集展开式,其展开系数是以线网几何参量为宗量的勒让德函数.该文的结果便于场的计算和分析并能够为线网屏平面的电磁屏蔽和场的反射等相关工程电磁场问题的研究提供的电磁场解析表达式.     

导电媒质平面上方垂直磁偶极源赫兹位函数的球面波展开式

精确有效地计算索末菲尔德型积分是分析导电媒质半空间电磁波辐射和散射问题的关键.本文给出求解有限导电媒质平面上方垂直磁偶极源赫兹位函数的解析方法.利用圆柱波函数的球面波函数展开式和超几何函数理论,位函数中的索末菲尔德积分被表示成快速、绝对收敛的球面波展开式;展开系数是以物性参数为复宗量的勒让德多项式.该展开式易于电磁场的计算和分析,并且不受场点和源点的位置、媒质的物性参数和频率等条件的限制.     

改进FGA优化设计T型微带线地平面结构

提出了一种新型模糊遗传算法(FGA)用于优化地参考面光子带隙(photonic bandgap,PBG)结构,降低高速电路中T型微带线串扰.该方法通过模糊控制器自适应调整遗传算子参数(杂交率和变异率),提高收敛速度并保证全局搜索能力.基于PML-FDTD法,适应度函数由串扰、反射损耗等各性能指标的加权构建,以此优化了PBG结构地参考面上T型微带线的串扰.对选用不同权系数的适应度函数进行仿真对比,其数值结果表明,采用该方法PBG参考面上的T型微带线对邻近线的串扰减小了8 dB,并且明显地降低了反射损耗和信号失真.     

薄层等离子体增强微波接收特性实验及数值仿真

等离子体是一种多模式、宽频谱电磁介质,可以与不同波段电磁波相互作用,实现对电磁信号的调制。报告了薄层等离子体增强微波信号接收特性实验研究的初步结果,并进行了数值仿真分析。在实验中发现了薄层等离子体结构对微波电磁信号的接收增强效果;且这种技术不仅可以在较宽频带内提高天线接收到电磁辐射的强度,同时也保持了良好的微波信号质量。进一步建立了相应物理模型并对实验结果进行了数值仿真分析研究。基于局域表面等离子体激元理论,分析了微波接收信号增强的机理,并初步得到了微波频率、薄层厚度、碰撞频率等参数对微波接收增强特性的调制规律。     

高阶张量阻抗边界条件的纵向电磁场分量表达式

首先导出转换矩阵表示的有导体或各向同性介质衬底的旋转对称双各向异性媒质平面的精确阻抗张量。然后利用多项式近似和横向与纵向场分量的基本方程组推导出相应的近似高阶张量阻抗边界条件。该阻抗边界条件是用纵向电磁场分量表示的二个关系式,表达式中的阻抗和导纳算符是介质涂层平面法向导数的三次幂多项式。所导出的高阶张量阻抗边界条件能够直截了当地模拟双各向异性介质涂层对电磁场的影响,并能够方便有效地简化相关电磁场边值问题的求解。     

Boundary conditions: An effect of average of microscopic Maxwell’s equations

ItisoftenstatedthatthedifferentialMaxwell’se quationsofmacroscopicelectrodynamicsareanaverageofthecorrespondingmicroscopicoratomicequations .Theinvestigationontherelationbetweenthemacroscopicandmicroscopicfieldequationsisanimportanttopicinelec tromagnetictheory .Firstlybecauseitisanessentialstepinrelatingempiricalmacroscopicelectromagneticphenom enatomicroscopictheory ,andsecondly ,becauseamis understandingofthisrelationcanmakeitalmostimpossi bletoachievealivelyandintuitivecomprehensionofthes…     

Improvement of Azimuthator Based on Particle Simulation

The azimuthator is an important part of plasma optical mass separation.The existing design for an azimuthator is based on the single particle orbit theory and focused on the movement of ions.In this paper,the particle simulation method is adopted to study the behavior of plasma crossing an azimuthator.The results show that electrons are bounded at the entrance of the azimuthator and an axial electric field is produced due to the charge separation.In order to better achieve the function of the azimuthator,a cathode is designed to transmit the electrons and to obtain a quasi-neutral plasma beam.     

Studies on omnidirectional enhancement of giga-hertz radiation by sub-wavelength plasma modulation

The technology of radio frequency (RF) radiation intensification for radio compact antennas based on modulation and enhancement effects of sub-wavelength plasma structures represents an innovative developing strategy.It exhibits important scientific significance and promising potential of broad applications in various areas of national strategic demands,such as electrical information network and microwave communication,detection and control technology.In this paper,laboratory experiments and corresponding analyses have been carded out to investigate the modulation and enhancement technology of sub-wavelength plasma structure on the RF electromagnetic radiation.An application focused sub-wavelength plasma-added intensification up to ～7 dB higher than the free-space radiation is observed experimentally in giga-hertz (GHz) RF band.The effective radiation enhancement bandwidth covers from 0.85 to 1.17 GHz,while the enhanced electromagnetic signals transmitted by sub-wavelength plasma structures maintain good communication quality.Particularly,differing from the traditional RF electromagnetic radiation enhancement method characterized by focusing the radiation field of antenna in a specific direction,the sub-wavelength plasma-added intensification of the antenna radiation presents an omnidirectional enhancement,which is reported experimentally for the first time.Corresponding performance characteristics and enhancement mechanism analyses are also conducted in this paper.The results have demonstrated the feasibility and promising potential of sub-wavelength plasma modulation in application focused RF communication,and provided the scientific basis for further research and development of sub-wavelength plasma enhanced compact antennas with wide-range requests and good quality for communication.