近地水平接地天线的数值分析

用矩量法（MoM）结合离散复镜像理论（DCIM）研究了有耗地面上方水平接地天线的性能以及天线之间的互耦。由离散复镜像理论得到了分层媒质中空域磁矢位格林函数和电标位格林函数的闭合表达式，避免了直接作索末菲积分。讨论了对接地点的处理方法，提出以集中加载的接地电阻来描述接地点地网特性，并在天线末端附加一个电流项，此外无须再寻求任何关于末端电流的终端条件。提出采用分段辛普森数值积分方法来计算检验源和展开源重合时的阻抗矩阵元素，最后给出了部分计算结果，并与文献数据进行了对比。     

TS-03全固态PDM中波发射机开关机控制电路工作原理及常见故障分析

在现阶段,中波广播的传输发射普遍使用的是全固态PDM中波发射机。在中波广播事业的发展中,发射机的不可替代性决定了其地位和作用,因此对发射机的运行及维护相关知识的了解至关重要。本文基于TS-03全固态PDM中波发射机展开论述,探讨其开关机控制电路工作原理,分析发射机常见故障及检修思路,以供参考。     

优化算法在手征媒质中的应用研究

由于手征媒质的手征参数可调性,使它成为一种新型的吸波材料,在减缩目标雷达散射截面方面有巨大的应用前景.文中运用传输线法分析了金属衬底上涂敷手征媒质的反射特性,计算了手征参数对手征媒质反射特性的影响;然后基于非均匀有理B样条建模,采用物理光学法比较了目标涂敷常规吸波材料与手征媒质时的雷达散射截面,结果说明了手征媒质减小反射电磁波的效果更好;最后运用粒子群算法和模拟退火算法在给定的范围内优化手征参数,并计算了在此参数下目标的散射截面.     

太赫兹波辐射源的研究进展

电磁波谱中的太赫兹波段拥有许多比传统光源更独特的性质,在生物、材料、安检和通信等领域有着非常重要的研究价值,而高功率和高效率的太赫兹辐射源则是太赫兹技术转化为实际生产力的一个重要因素和前提条件.文章分别从以气体、固体和液体作为激发介质的角度,总结了激光与不同激发介质相互作用产生太赫兹波的研究进展.对气体介质中常用的四波...     

太赫兹介电谱与组分含量的关系分析及应用

研究了固体有机样品的太赫兹介电谱与组分体积含量之间的关系。通过分析有效介质理论中的CRI（Complex Refractive Index）模型,得到样品的介电参数与组分体积含量的关系式。利用太赫兹时域光谱技术测得室温下两种氨基酸样品在0.5～2.7 THz的介电性质,样品的折射率、介电系数及介电损耗均随氨基酸体积含量增加而增大。选取氨基酸介电损耗谱特征峰位处的介电参数,根据CRI模型进行拟合,得到折射率与体积含量的线性关系式,介电系数和介电损耗与体积含量的二次函数关系式。研究结果有利于扩展太赫兹波段的定性定量分析手段,并对聚合物基复合材料制备有一定参考意义。     

圆对称高斯光束在吸收克尔介质中的稳态自聚焦行为

由光束在吸收克尔介质中传输的非线性近轴波方程 ,推导出具有二次相位分布的圆对称高斯光束在线性吸收介质中的耦合传输方程以及光束束腰的演化方程。数值计算的方法证实了光束束腰变化的几种可能 ,分析了稳态自聚焦的阈值特性。在给定参数的情况下 ,得到了稳态自聚焦的阈值入射光强和阈值聚焦长度     

电磁波多层媒质传播的[C]网络新理论

本文讨论电磁波在多层媒质中传播的反射和折射。将电磁波斜入射到媒质突变的平面边界作为基本模型,推广到垂直入射和导体、磁体边界等多种情况。本文将电磁波传播和网络理论有机结合,创新地提出多层媒质的[C]网络理论,从而把困难的多层媒质传播转化为[C]矩阵级联,概念简单,结果统一。文中还给出了具体实例。     

Industrial wireless sensor and actuator networks in industry 4.0: Exploring requirements,protocols, and challenges—A MAC survey

The vision to connect everyday physical objects to the Internet promises to create the Internet of Things (IoT), which is expected to integrate the diverse technologies such as sensors, actuators, radio frequency identification, communication technologies, and Internet protocols. Thus, IoT promises to transfer traditional industry to advance digital industry known as the Industry 4.0. At the core of the Industry 4.0 are the wireless sensor networks (WSNs) and wireless sensor and actuator networks (WSANs) that led to the development of industrial wireless sensor networks (IWSNs) and industrial wireless sensor and actuator networks (IWSANs). These networks play a central role of connecting machines, parts, products, and humans and create a diverse set of new applications to support intelligent and autonomous decision making. The IWSAN is a promising technology for numerous industrial applications because of their several potential benefits such as simple deployment, low cost, less complexity, and mobility support. However, despite such benefits, they impose several unique challenges at different layers of the protocol stack when deploying them for various monitoring and control applications in the Industry 4.0. In this article, we explore IWSAN, its applications, requirements, challenges, and solutions in the context of industrial control applications. Our main focus is on the medium access control (MAC) layer that can be exploited to satisfy such requirements. Our discussion presents extensive background study of the MAC schemes and it reviews the MAC protocols of the existing wireless standards and technologies. A number of application‐specific MAC protocols developed to support industrial applications, which are not part of these standards, are also elaborated. We rationalize to what extent the existing standards and protocols help in solving such requirements as laid down by the Industry 4.0. In the end, we emphasize on existing challenges and present important future directions.     

PCB层间介质层厚度探讨

PCB生产实践中,有阻抗控制要求的印刷板,需在PCB制造中对板材的介电常数、导线的宽度和厚度、结构等加以控制,多层板中一旦特性阻抗控制不好,造成高速传输信号过程中和终端出现损耗损失、衰减失真、信号重叠、杂乱等现象,因此必须严格管控PCB层间介质层厚度。本文通过对PCB层间介质层厚度探讨,并针对此进行设计改善、控制。     

Threshold gain properties of lasing modes in ID disordered media optically pumped by femtosecond-lasing pulse

By numerically solving Maxwell's equations and rate equations,a comprehensive calculation on spectrum intensity and spectral widths of three localized modes via different pumping rates in one-dimension...