| Based on environmental electromagnetic radiaton pollution source surveys,this paper described the kinds,distribution,radiation power and development tendency of present electromagnetic equipments.By predicting field intensity of typical electromagnetic equipments,the attenuation characteristics,including electric field distortion and non-distortion are researched combined with a large number of measured comprehensive field intensity.According to frequency distribution statistical results of field intensity and power density,and relative domestic standards, protection distances of 5 typical electromagnetic equipments are proposed relatively. On the basis of investigating the environmental electromagnetic status differences between urban and rural areas,as well as diferent function areas in cities,technical specification for environmenatl electromagnetic function districts programming has been proposed with reference to technical specification for other enviroment elements. A case study of Xihu area in Hangzhou is analyzed.This research is benefit for the management of present electromagnetic equipment,and provides scientific basis for electromagnetic environment controlling.Main conclusions are as following:(1)By investigation and statistics of 5 provinces and cities electromagnetic equipment,the results shows that in the year of 2005,the quantities of mobile base stations in Hubei Province,Shanghai and Baotou is 48.3%of total amount in 1998. Compared with the national total amount in 1998,the number of HV transmission lines in 5 provines and cities increased to 2.1 times,while the radiation power of broadcast and TV towers in Hubei Province and Baotou increased to 1.6 times.The sum radiation power of ISM equipment in Hubei Province and Shanghai is 94.7%of total national radiation power in 1998.The electromagnetic environment background value are in the range of 0.2V/m～1.6V/m,which are lower than domestic environmental and hygienic standards.(2)Based on different frenquency bands of typical radiofrequency sources,this paper uses electromagnetic wave free space propagation model,power density prediction model in far-field to predict the field intensity and power density of medium broadcast tower and FM radiation tower,mobile base stations with different numbers of carders,radars and nevigation equipments,the distribution of power frequency electric field intensity with different voltage grades,height above the ground,numbers of circuits and splitting conductors,phase sequence,transmission lines are calculated by using charge equivalent method,the magnetic field intensity and radio interference disturbance are predicted as well.Comparing with the theoretical and measured results,comprehensive field intensity is lower than relative environmental and hygienic radiofrequency standards at the horizontal projection distance of 300m and 250m,for medium wave broadcast tower and FM television tower.The distance of 300m agrees with measured distance,because of high frequency of electromagnetic wave FM television radiated and absorption and scattering of walls and grounds.Comprehensive field intensity of mobile base stations is lower than at 30～35m public exposure limit,while radar and nevigaton equipment is at the range of 30～40m.There are few monitoring points exceeding the standards. Voltage glades,interphase spacing and height above ground affect the distribution of power frequency electric field intensity.HV transmission line with voltage above 110kV will exceed the standards.The maxmium electric field intensity appears at the range of 0～10m.Measured magnetic intensity and radio disturbance are lower than than theoretical results and power frequency electromagnetic radiation standards. Electromagnetic field intensity caused by traffic services such as subways and light-railways reduces under 1/3 of standrads at the distance of 30m.Field intensity caused by ISM equipment can reach to more than 100V/m in the range of 3m,which can result in a fast attenuation.Protection distances of 5 typical electromagnetic equipments are proposed by 50%frequency distribution statistic analysis results of 773 mobile base stations and HV transmission lines with different distance ranges,considering the typical equipment distrbution status and with reference to domestic environmental and hygienic standards.Protection distance of medium wave radiation tower and FM radiation tower are 800m and 600m respectively.Protection distance of mobile communication base station is 40m,which for radars and navigation equipment is 200m.Protection distance of ll0kV HV transmission line is 10m,220kV HV transmission line is 20m,500kV HV transmission line is 50m,transformer substations is 30m.The distance of ISM equipment is 50m.Electromagnetic environment background value is monitored through 4 seasons, and differences about numbers,distribution and radiation power between urban and rural areas are analyzed.Different function areas in cities are monitored using mesh points method,the data are analyzed by statistic methods.Results show that, electromagnetic environment background value in urban areas is nearly three times than in rural areas.Scenic area and residential areas are highest and lowest average electromagnetic value areas respectively if the statistic results of cumulative distribution 50%is stand for average value.(3)This paper uses the statistic results of cumulative distribution 90%in different distance near mobile base stations,HV transmission lines and electromagnetic environment background in a lot of cities for theoretical basis of function areas evaluation limits with reference to radiation differences of typical radiation sources, function areas programming with other environmental elements and environmental and hygienic radiofrequency standards in and abroad.The limits of 1～3 types for power frequency electromagnetic field is 1kV/m,4kV/m and 10kV/m respectively, while for radio frequency electromagnetic filed is 1.5V/m,5V/m and 30V/m respectively.The applicable regions,division priciples and methods.Function district 3 is applicable to the neighborhood area of the broadcast television launching tower (including the medium wave broadcast program and the FM television launching tower)at the range of 400m±20m,and the both sides of the level of 220 kV transmission line in the range of 40m±5m.Function district 2 is applicable to the commercial and industry commixing district,the commercial programming district, the industrial programming district,industrial centralize zone and the proper area of the broadcast television launching tower in the range of 400～1000m and the transmission line in the range of 40 to 60m.
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