Petersen R C, Testagrossa P A
Radiation Protection Department, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.
Bioelectromagnetics. 1992;13(6):527-42. doi: 10.1002/bem.2250130608.
Because of a heightened public awareness of issues pertaining to the use of electromagnetic energy, concurrent with a rapid growth of the cellular telephone industry, a study was initiated to characterize the electromagnetic environment associated with typical cell-site antennas. In particular, the radio-frequency electromagnetic (RF) fields in the vicinity of several antenna towers, ranging in height from 46-82 m, were characterized by measurement. In all cases, the antennas were omnidirectional co-linear arrays. The maximal power densities considered representative of public exposure were found to be less than 100 microW/m2 (10 nW/cm2) per radio channel. Comparison of measured values with the corresponding values that were calculated from the free-space transmission formula indicated that the analytical technique is conservative (i.e., overestimates field levels). The measured and corresponding analytical values were found to be well below accepted exposure limits even when extrapolated to simultaneous and continuous operation of the maximal number of transmitters that would be expected to be installed at a cell-site. Additional measurements were made in the near field of the same antenna type in a roof-mounted configuration. At a distance of 0.7 m from the antenna, the maximal power density in the main beam was found to be less than 30 W/m2 (3 mW/cm2) when normalized to sixteen radio channels (the maximal number used on a single antenna) and less than 30 mW/m2 (3 microW/m2) at 70 m. In all cases, the effective radiated power (ERP) by each radio channel was 100 W referenced to a half-wave dipole. This paper describes the instrumentation and measurement techniques used for this study and provides a summary of the results.
由于公众对与电磁能使用相关问题的关注度提高，同时蜂窝电话行业迅速发展，因此启动了一项研究，以描述与典型基站天线相关的电磁环境。具体而言，通过测量对几座高度在46至82米之间的天线塔附近的射频电磁场（RF）进行了表征。在所有情况下，天线均为全向共线阵列。发现代表公众暴露的最大功率密度每个无线电信道小于100微瓦/平方米（10纳瓦/平方厘米）。将测量值与根据自由空间传输公式计算出的相应值进行比较表明，分析技术较为保守（即高估了场强水平）。即使外推到预期在一个基站安装的最大数量发射机的同时连续运行，测量值和相应的分析值也远低于公认的暴露限值。还对同一类型天线在屋顶安装配置下的近场进行了额外测量。在距天线0.7米处，当归一化为16个无线电信道（单个天线使用的最大数量）时，主波束中的最大功率密度小于30瓦/平方米（3毫瓦/平方厘米），在70米处小于30毫瓦/平方米（3微瓦/平方厘米）。在所有情况下，每个无线电信道的有效辐射功率（ERP）相对于半波偶极子为100瓦。本文描述了本研究中使用的仪器和测量技术，并提供了结果总结。
