南充市移动通信基站电磁辐射环境调查及防护

调查该地区移动通信基站周围环境电磁辐射现状,采用PMM8053B主机及EP33M探头对62台基站电磁辐射综合场强和功率密度进行测量和分析,分别从点位、基站制式以及基站分布地域差异3方面特征分析功率密度变化规律,并给出相应的防护意见。结果表明调查的基站周围电磁辐射功率密度均未超过国家标准限值。     

移动通信基站电磁辐射实例分析

随着移动通信技术的发展，基站的电磁辐射受到越来越多的关注。本文介绍了分析移动通信基站的电磁辐射情况预测模型，结合天线的方向性和增益情况对不同地区不同辐射方向上的电磁辐射情况做出预测并与实测数据进行比较分析。     

基于AMC加载的高增益60GHz天线

针对如何在不改变天线结构的前提下增大天线增益的问题,采用了AMC（人工磁导体）加载的方法。设计一款圆环缝隙AMC加载的天线,通过对AMC相位的改变来优化天线。设计的加载天线包括AMC和60GHz微带贴片天线,该加载天线拥有10GHz（55GHz-65GHz）的带宽和5.6dBi的增益;实验结果表明,相比没有加载之前的天线,加载天线拥有相同的带宽,其增益提高了2.9dBi。     

电磁辐射环境分析与测量

电磁辐射环境是指设备或系统在执行规定的任务时，可能遇到的辐射发射电平在不同频率范围内功率和时间的分布，本文对飞机飞行区域和机内的电磁辐射环境以及空中发射武器所处的电磁辐射环境进行了分析，同时还讨论了试验室内的电磁环境电平大小对电磁兼容性试验、雷达截面和天线方向图测试精度的影响，以及电磁辐射环境的测量方法。     

220千伏高压输电线路对电磁环境的影响分析及防治对策

通过对220kV输电线路电磁辐射的实际测量和理论计算,研究和讨论了220kV单回路和双回路输电线产生的电磁辐射对环境的影响,并提出降低电磁辐射水平的对策与建议。     

大功率中短波广播天线电磁辐射的预测与防护

随着城镇密集度越来越高,大功率电磁辐射设备如大功率中短波天线不可避免的与建筑越来越近,因而对室内的电磁环境污染逐步加剧。电磁辐射造成的危害通常包括对人体健康的危害(健康效应)和干扰其他电磁设备而造成严重后果(电磁干扰)。针对大功率中短波天线造成的电磁环境污染问题,提出一套远场条件下电磁辐射的预测方法并成功预测了一个典型大功率中短波天线群附近的拟建项目区域的电磁环境,在此基础上,提出有效的针对拟建项目的电磁防护方案。     

成都市区电磁辐射设施应用与环境水平关系研究

本文介绍了成都地区目前应用的主要电磁辐射设施,并根据其不同辐射特性,确定了调查因子。在此基础上,对成都市主城区进行网格布点监测,根据监测结果,分析归纳出成都市区电磁辐射设施应用与电磁环境水平之间的关系。     

电磁辐射设施应用与环境水平关系研究——以四川广播电视塔为例

为掌握四川广播电视塔所产生的电磁辐射对公众的影响,本文分析了位于成都市区的四川广播电视塔的辐射特征,根据相关规范制定了监测方案,并进行了射频综合电场监测。通过分析不同方向和高度的监测结果,归纳电磁辐射设施应用与电磁环境水平之间的关系,得出了四川广播电视塔周围公众居留位置处电磁辐射满足国家标准的结论。     

关于《5G移动通信基站电磁辐射环境监测方法(试行)》监测工况的探讨

为完善《5G移动通信基站电磁辐射环境监测方法(试行)》标准,解决可能存在的按照试行标准监测工况得到的结果与实际5G基站电磁辐射值不一致的问题,对5G基站电磁辐射原理与5G业务流量模型进行了理论分析,用实验验证的方法探讨了不同监测工况(即5G业务流量模型)对5G基站电磁辐射监测结果的影响,提出了一种新的基于5G业务流量模型的监测工况定义,并建议以标准实施细则的方式予以施行。     

现行中波项目电磁辐射环境影响预测模式的保守性验证

本文验证了目前中波项目电磁辐射环境影响预测模式的预测结果相对于实测结果来说是保守的.从公众健康的安全角度考虑这种保守是可以接受的,这在项目环境影响评价中有利于我们依据预测结果制定有效的防护措施,从而在项目建成之后使其对环境的影响达到国家相关标准、规范的要求.     

Analysis of radiation hazards to personnel on marine platforms

The large number of radio frequency (RF) transmitters employed in modern marine platforms requires that they operate in mutual coexistence while posing no danger to operators and equipment despite the limited available physical space. A key to the successful system integration is the control of the electromagnetic environment on the ships’ topsides, which might pose radiation hazards (RADHAZ) to personnel (HERP). HERP are caused by transmitter antenna installations that generate intentional EM radiation in excess of the safe levels in zones of personnel activity. Radiation safety to personnel is achieved when the average radiation power density is below the permissible exposure limits (PEL) for HERP at locations of personnel activity and medical equipment operation. This paper describes the analysis tools and techniques for the evaluation of HERP on marine platforms. The same approaches could be employed in the analysis of land site antenna deployment scenarios.     

Interaction Between GSM Handset Helical Antenna and User's Head: Theoretical Analysis and Experimental Results

Summary The performance of a cellular phone commercial helical antenna at 900~MHz band, both in free space and in the presence of a human head phantom was studied. Numerical simulation of the phone model for the latter case has been performed giving 3D radiation diagrams. The effect of the phantom head on radiation diagrams is presented. The relative amount of the EM power absorbed in the head was obtained for several distances of the phone. Measurements were carried out in a RF anechoic chamber using standard horn antennas and a calibrated measuring system. Absolute radiation patterns of the antenna gain were obtained in the three principal planes. Significant reduction of the absorbed power could be achieved just by moving the phone 1 cm away from the head.     

Effects of in vitro exposure to GSM900 electromagnetic field on human erythrocytes

High frequency electromagnetic fields (EMF) are widely used for transmitting of radio and TV signals, in wireless communications, etc. A huge number of people are exposed so the possible risk to human health from telecommunication technologies could be significant even if biological effects are slight. The study of the biological effects of RF EM radiation could contribute to better understanding of the possible health hazards. The levels of released hemoglobin serve as an indicator of hemolysis, caused by increased membrane fragility. This study was designed to investigate the alterations in hemoglobin release after in vitro exposure of human erythrocytes to GSM900 electromagnetic field. Erythrocyte suspensions with two different cell concentrations (hematocrit 20% and 40%) were exposed to EM radiation from GSM mobile phone (carrier frequency 902 MHz, 2 W output power in pulse) for 20 min in two different positions in relation to telephone antenna: Position 1 is in the centre of the major lobe of the azimuth antenna pattern and Position 2 is between major and back lobes. Alterations in hemolysis were registered 0, 10, 20, 30, 40, 50 and 60 min after the treatment. Hemolysis was determined by measuring the absorbance of hemoglobin at 413 nm in the supernatant obtained by centrifuging the suspensions. Hemolysis was expressed as hemoglobin concentration. Our data indicated decrease in the hemoglobin level in irradiated suspensions. The GSM900 EMF exposure probably stabilized erythrocyte membrane and caused reduction in the hemolysis depending on the EMF parameters, on the suspension water content (hematocrit) and on the time elapsed after irradiation.     

A Graphical Method for the Estimation of Radiation Hazards from a Crowded Multiple Antenna Site

Summary The major objective of the design of safe crowded transmitting antenna sites is not only to determine a safe zone around each individual antenna; rather, to establish safety areas at the antenna site itself, as well as, at the neighboring areas. The requirement is to ascertain the safety regions by considering the following parameters at each Test Point (TP) (or area segment): the contribution of N co-located radiating antennas to the total radiation incident at the TP, the radiation pattern of each antenna, the near/far field region of each antenna, and most importantly, the different Permissible Exposure Limits (PELs) associated with each operating frequency at the antenna site. Implementation of all the above-mentioned aspects in a suitable computer requires resources that only expert knowledgeable organizations possess. The graphically aided tool presented in this paper facilitates the calculation of a “safety zone” for RADHAZ around a crowded antenna site from the knowledge of the “safety ranges” which correspond to the individual transmitting antennas comprising it.     

对新疆当前电磁辐射环境管理的认识

随着现代科学技术的进步和发展,在电磁辐射的运用范围越来越广的同时其污染水平也在不断增高,人类生存的环境也在不断受到电磁辐射的影响,加强电磁辐射环境管理已势在必行。通信系统电磁辐射应是新疆当前电磁辐射环境管理的重点。     

Influence of the Interaction of a 900 MHz Signal with Gender on EEG Energy: Experimental Study on the Influence of 900 MHz Radiation on EEG

Summary The effects of electromagnetic fields (EMF) emitted by cellular phones on human electroencephalogram (EEG) were studied during an auditory memory task. The experimental method and the experimental setup are introduced as a credible measurement method of EEG. 19 normal subjects (10 women and 9 men) performed the memory task both with and without exposure to a 900 MHz signal, emitted by a dipole antenna placed near the subjects' head. The energy of the EEG signals was calculated at the time domain. A Fourier transform of the EEG signals was done and the EEG energy was also calculated at the frequency domain. As the Parseval's theorem anticipates the energies were identical. The EEG energy was found concentrated at the four basic bands (α (8–13 Hz), β(14–30 Hz), δ (0–4 Hz) and θ(5–7 Hz)). The primary concern of the present study was the gender related influence of EMF on the spectral energy of EEG. The results show evidence of a strong gender—radiation interaction effect on the EEG energy and on the peak amplitudes within each of the four rhythms. Without radiation the spectral power of males is greater than of females, while under exposure the situation is reversed. Under the influence of EMF the spectral power of the males EEG is decreased while that of the females is increased. In conclusion both the baseline EEG and the changes effected to the EEG power spectrum under the influence of EMF seem to be gender dependent.     

大功率电磁加热系统电磁兼容性分析设计技术探讨

文章对大功率电磁加热系统的电磁兼容性进行了分析,针对系统中的主要电磁干扰源,从传导干扰以及辐射干扰的角度对这些干扰的产生机理进行了分析。从电路布局设计、屏蔽技术两个方面提出了一系列抑制干扰的方法与原则。可为大功率电磁加热系统的设计提供参考。     

浅谈电磁辐射对人体的危害与防护

电磁辐射对人体的危害作用表现为热作用、非热作用、刺激作用及累积作用。对电磁波辐射进行控制采取的技术对策主要包括两个方面：一是通过优化电路设计、配线分离，包括含接地线的线路板设计；二是采用各种防护材料。最后，对电磁辐射的个人防护提出几项建议。     

大型自然通风冷却塔环境影响的预测分析研究

大多数内陆核电厂将采用大型自然通风冷却塔作为其二次循环冷却方式,本文基于美国核管会推荐的SACTI程序,给出了该模型的基本原理和框架结构,并以江西彭泽核电厂为例,采用该程序预测分析了该核电厂大型自然通风冷却塔所造成的雾羽和太阳辐射损失的影响。并进一步研究了不同环境风速、相对湿度条件下对冷却塔造成的太阳辐射损失的影响。SACTI模型可以根据厂址逐时气象观测数据,较好地计算可见雾羽的长度、抬升高度和太阳辐射损失,其结果可以作为冷却塔环境影响评价的依据。