雷达电磁辐射的危害与防护

电子产品在使用过程中会产生电磁辐射,电磁辐射的强度和时间超过一定限度就会造成电磁污染,危害人们健康。电磁辐射主要通过热效应、谐振效应和累积效应三种方式对人体产生影响。雷达作为部队常见装备被广泛应用于诸多军事任务中,多数军用雷达在使用过程中会产生较强的电磁辐射,对装备性能及官兵身心健康造成较大负面影响。文章主要阐述了雷达电磁辐射的致害原理和对官兵的身心危害,并提出了具体的防护措施。     

电磁波强场强区域对人体的影响与防护

利用电磁波在各个领域为人类现代生活服务的同时,根据电磁波的特点及对人体的影响、损害和防护是我们必须关注的.电磁波辐射作用,可分为近场区、远场区.导体、电介质在电场中的体现出的现象,是其内在原因所决定的.根据麦克斯韦方程分析,导电媒介质中的电磁波的性能,及电磁波在导体中的传播特性.生物体可以视为具有复杂形状的有机电介质结构.电磁辐射对生物的作用机制,基本上可分为致热效应、非致热效应.根据在电磁波环境下工作的人员病理调查实例,及具体工作区的电场强实测,提出发射机房的电磁防护要求和措施.     

电磁波强场强区域对人体的影响与防护

利用电磁波在各个领域为人类现代生活服务的同时,根据电磁波的特点及对人体的影响、损害和防护是我们必须关注的.电磁波辐射作用,可分为近场区、远场区.导体、电介质在电场中的体现出的现象,是其内在原因所决定的.根据麦克斯韦方程分析,导电媒介质中的电磁波的性能,及电磁波在导体中的传播特性.生物体可以视为具有复杂形状的有机电介质结构.电磁辐射对生物的作用机制,基本上可分为致热效应、非致热效应.根据在电磁波环境下工作的人员病理调查实例,及具体工作区的电场强实测,提出发射机房的电磁防护要求和措施.     

手机的辐射及其防护

一、电磁辐射的来源 电磁辐射是指能量以电磁波形式由源发射到空间的现象。电磁环境是存在于给定场所的所有电磁现象的总和。由于人类社会的发展,科学技术的进步,城市规模的扩大,城市中电磁辐射环境日益恶化。 造成电磁污染的原因有很多方面：市区扩大,使得原处郊区的大功率电磁发射台逐渐被新建居民区所包围;卫星通信的发展使得城市近郊区出现众多卫星地面站,有的地区发射天线已超过２０个;移动通信技术发展迅速,市区高层建筑上移动通信基站天线林立,部分架设不合理的天线造成高层居民楼电磁环境污染;城市交通运输系统形成的电磁…     

高功率干扰设备电磁辐射危害性及防护分析

电磁辐射危害人体健康,如不采取必要防护措施,长期接触会造成不可恢复的严重伤害。强功率干扰是电磁作战的必要手段,接触干扰设备的作战人员不可避免地会受到电磁辐射影响。针对电磁辐射的危害,对人体受害机理、典型防护措施和安全限界标准进行了简要介绍,在分析电磁波辐射场传播特性的基础上,对L频段高功率有源相控阵干扰设备的电磁辐射场强进行计算,明确了安全工作条件,提出了具体的安全防护措施。     

一种新的个人唯一通信业务系统

移动通信或个人通信的优点在于满足人们随时随地沟通的需求。但由于移动通信对移动终端的依赖大，长期使用手机对人们的隐私和安全带来一些社会问题。当我们用手机打电话时，音频信号经过手机转换为高频率的电信号，然后通过灭线以电磁波的形式发射出去，这时在手机附近就会产生较为强烈的电磁辐射。手机的工作频率大多为900多兆赫，双频为1800多兆赫，均属于微波波段。电场与磁场都是物质存在的一种形式。     

设备电磁辐射的评价与测量方法

随着经济发展和物质文化生活水平的不断提高,家用电器和高科技产品广泛普及。各种家用电器和电子设备在使用过程中均会产生不同的电磁波,对人体具有潜在危害,形成所谓的＂电磁污染＂。文中提出了多种电磁辐射评价方法和测量方法,并简要介绍了测量仪器等。     

浅析移动电话的安全使用

如今,移动电话已经成了人们日常生活中不可或缺的通信工具之一。在移动电话给人们工作、学习和生活带来诸多便利的同时,移动电话的电磁辐射也带给了人们一些担心。如何安全使用移动电话和正确认识移动电话产生的电磁辐射,对移动电话的用户来说是十分必要的。一、移动电话的电磁辐射怎样对人体构成危害众所周知,移动电话是通过向空间发射电波来进行通信联系的。发话时,移动电话将音频信号转换为高频电信号,经过天线以电磁波的形式发射出去,这时移动电话的天线附近会产生一定的电磁辐射。移动电话工作功率很小,其电磁辐射强度在一定范…     

加强对非无线电设备电磁辐射的管理

加强对非无线电设备电磁辐射的管理郝健，高云，李荣鳌非无线电设备在工作中所形成的电磁辐射，构成了对周围的电子设备及人类生活环境的严重污染和对人体健康的危害，因而电磁污染已被列为公害之一。加强对非无线电设备电磁射辐的管理，是无线电管理工作的任务之一。《条...     

利用无线电发射、接收电路制成的地震前电场异常预报器

地震前出现电磁波现象已经由许多实例证实,国内外现场观测和室内岩石样品压力实验的结果表明,震前岩石破裂电磁辐射的频谱是很宽的,包含了电磁波的各个频段。利用业余无线电发射、接收电路制成的电磁异常检测器,就是利用了临震阶段可能有某种与地震有关的较高电平和较宽频谱的异常电磁辐射信号出现。以简单的钟表机芯每分钟接通5秒钟,驱动业余无线电发射、接收电路工作、由此同时选用光电报警电路做成的临震预报装置。利用电磁异常检测器专门用来地震前监视空间电场变化,由于震前电磁波现象是客观存在的,其物理基础是清楚的,所以是一种有希望的地震短临预报方法。     

应用电磁波剔除早期失效的半导体器件

本文根据在横电磁波作用下半导体中载流子运动方程的解说明了电磁波对半导体器件同时具有热与非热效应作用。用实验证实了电磁波对半导体器件参数的影响,并给出了一批产品的早期失效曲线。说明了应用电磁波剔除早期失效半导体器件具有时间短,安全的优点。最后介绍了试验的系统和设备。     

Nonsinusoidal Waves in Cavity Resonators

It has been shown that nonsinusoidal waves can propagate dispersion-free in loss-free waveguides. This situation opens the possibility of nonsinusoidal waves existing distortion-free in cavity resonators. A general solution of Maxwell's equations for nonsinusoidal waves in rectangular cavity resonators is derived. For the special case of a square wave, the electric and magnetic field strengths as functions of time and space are analyzed in detail. The implication of this analysis is that square waves or other periodic nonsinusoidal waves with various periods T can be separated by cavity resonators just as sinusoidal waves with various periods T can be separated. This paper is part of an ongoing effort to advance the technology of antennas and associated circuits for nonsinusoidal electromagnetic waves.     

Wave propagation and dipole radiation in a suddenly created plasma

Propagation and radiation of electromagnetic waves from oscillating sources in a suddenly created plasma are studied in this investigation. Field expressions are derived through the use of Laplace transformations. The spatial distribution of sources is taken to be arbitrary but confined. Two cases are considered in detail: 1) plane wave propagation in a source-free region and 2) electric point dipole radiation. In the case of plane wave propagation, various aspects such as wave split, frequency shift, phase and group velocities, amplitude changes, power flows, and energy relations are discussed. In the case of electric dipole radiation, the electromagnetic fields and instantaneous radiated power are calculated and expressed in terms of Lommel functions of two variables. Asymptotic expressions and graphical results of numerical calculations of these quantities are presented. Many interesting properties of the spherical waves and power radiation are discussed.     

表面波放电狭缝天线辐射电磁场的三维数值分析

针对平板型表面波放电等离子体源,建立了表面波放电狭缝天线辐射电磁波模型,对狭缝天线辐射电磁场分布进行了三维数值计算,并与表面波电磁场进行对比分析,讨论了平板型表面波放电机理。结果表明:整个狭缝天线阵激发的电磁场是每个狭缝天线激发电磁场的线性叠加;狭缝天线阵直接激发的电磁场强度在临近波导壁面处很大,并且随着空间距离的增大迅速衰减;狭缝天线阵直接激发和表面波的电场均远大于各自的磁场,分析电、磁场对带电粒子的力作用时可以忽略磁场力的作用;表面波电磁场远大于狭缝天线阵直接辐射的电磁场,强电磁场范围也远大于狭缝天线阵直接激发的强电磁场范围,等离子体有增强电磁场强度、扩大强电磁场范围的作用。     

Excitation of electromagnetic waves in a gyroelectric cylinder

The coupling of electromagnetic waves originating from a dipole to an infinite gyroelectric cylinder is treated analytically. The anisotropy axis of the gyrotropic medium is assumed to coincide with the cylinder axis. An electric dipole type primary excitation, with an arbitrary axis of orientation, is considered and the dyadic Green's function is derived for the gyroelectric cylinder. The field inside the anisotropic medium is expressed as a superposition of transverse magnetic (TM) and transverse electric (TE) type waves and a purely longitudinal wave. Excitation of guided modes along the gyroelectric guide and radiation patterns of dipoles radiating in the proximity of the gyroelectric cylinder are analyzed and computed for several cases.     

电磁波极化形式的频域判据

电磁波极化的判定问题是电磁场理论教学中的重点和难点。当电磁波的电场分量和波矢量表达式是坐标基矢量的组合形式时,学生往往难以用右手定则判定其极化形式。本文从电磁波极化定义出发,结合有向曲线绕向的计算方法和复矢量运算法则,给出了极化形式的频域判据。学生直接对电场复矢量进行简单的矢量乘法运算即可完成判定,提高了解决此问题的效率和准确度。     

Fast Convergence Algorithm for Earthquake Prediction Using SLF/ELF Horizontal Electric Dipole during Day and Night and Schumann Resonance

Electromagnetic wave radiation from a SLF/ELF horizontal electric dipole (HED) related to seismic activity is discussed. In order to estimate the effects on the electromagnetic waves associated with the seismic activity, SLF/ELF waves on the ground radiated from a possible seismic current source modeled as a electric dipole, are precisely computed by using a speeding numerical convergence algorithm. A theoretical calculation of the VLF/SLF electric wave propagating among the Earth-ionosphere cavity generally utilizes the full wave method to solve the model equation. The field in the cavity is comprehended as the sum of each wave mode. However, this method is very complex, and unsuitable to the ELF frequency band. In 1999, Barrick proposed an algorithm, which was only suitable to solve the electromagnetic problems under the ideal electric conductor condition. To solve the problems under the non-ideal electric conductor condition, we have further developed Barrick??s method and proposed a speeding numerical convergence algorithm. The spherical harmonic series expressions of electromagnetic fields excited by SLF/ELF HED in non-ideal Earth-ionosphere cavity are derived. The speed of this algorithm is faster thirty times than it of calculating directly the sum of the series. If it calculates directly the sum of the series, it needs 1,000 series items, while it needs only 200 series items by this algorithm. Our algorithm is compared with the second order spherical surface approximate algorithm, and two algorithms agree with each other very well. Therefore, our algorithm is correct. Schumann resonance is also verified.     

Time-domain simulation of spherical electromagnetic waves

Spherical electromagnetic waves excited by external surface electric currents in a homogeneous isotropic space are considered. It is shown that, in contrast to the harmonic excitation, in the case when the electromagnetic field is excited by external-current pulses, there is always an isolated convergent spherical wave in a bounded space-time region. The possibility of the existence of an isolated convergent spherical wave in a bounded spatial region at all instants is investigated for the cases of harmonic and pulse electromagnetic field excitations. It is proved that such a wave can exist when the divergent spherical wave arriving from the origin is compensated with the use of additional external currents. The excitation of isolated convergent spherical waves is illustrated by examples.     

Radiation from an electromagnetic source in a half-space of compressible plasma-surface waves

The radiation characteristics of a line source of magnetic current are studied for the case in which the source is situated in a half-space of isotropic, compressible plasma which is bounded on one side by a perfectly conducting, rigid plane screen. In addition to the electromagnetic and plasma space waves, the line source excites a boundary wave. This boundary wave is a coupled wave. It has associated with it both a magnetic field component and the pressure term. This is in contrast to the space waves which can be decomposed into an electromagnetic (EM) mode with no pressure term and a plasma (P) mode with no magnetic field associated with it. The characteristics of this boundary wave are evaluated. The boundary wave propagates for all frequencies and the power carried by the boundary wave becomes smaller as the frequency is increased.     

Scattering of TE-polarized EM wave by discontinuity in groundeddielectric layer

The two-dimensional problem of EM wave interaction with a dielectric discontinuity in an infinite grounded dielectric layer is studied. An electric field integral equation (EFIE) for TE illumination has been derived based on the Green's function for the electric field produced by induced polarization currents in the discontinuity region. Impressed electric fields consist of either plane waves incident from space above the dielectric layer or surface waves supported by that layer. Method of Moments (MoM) numerical solutions for the induced electric field in the discontinuity region are implemented. The amplitudes of surface waves excited by excess discontinuity-region polarization currents are calculated, as well as the pattern of the scattered field and the associated scattering width. It is observed that the excitation of a surface-wave mode reduces the back scattered radiation for TE-polarized plane wave incidence. The accuracy of the theory is verified by comparison of numerical results with those of existing studies