Physical Dosimetry Department, Health Protection Agency, Chilton, Didcot Oxon, UK.
Health Phys. 2011 Jun;100(6):594-612. doi: 10.1097/HP.0b013e318200e203.
Laboratory measurements have been carried out with examples of Wi-Fi devices used in UK schools to evaluate the radiofrequency power densities around them and the total emitted powers. Unlike previous studies, a 20 MHz bandwidth signal analyzer was used, enabling the whole Wi-Fi signal to be captured and monitored. The radiation patterns of the laptops had certain similarities, including a minimum toward the torso of the user and two maxima symmetrically opposed across a vertical plane bisecting the screen and keyboard. The maxima would have resulted from separate antennas mounted behind the top left and right corners of the laptop screens. The patterns for access points were more symmetrical with generally higher power densities at a given distance. The spherically-integrated radiated power (IRP) ranged from 5 to 17 mW for 15 laptops in the 2.45 GHz band and from 1 to 16 mW for eight laptops in the 5 GHz band. For practical reasons and because access points are generally wall-mounted with beams directed into the rooms, their powers were integrated over a hemisphere. These ranged from 3 to 28 mW for 12 access points at 2.4 GHz and from 3 to 29 mW for six access points at 5 GHz. In addition to the spherical measurements of IRP, power densities were measured at distances of 0.5 m and greater from the devices, and consistent with the low radiated powers, these were all much lower than the ICNIRP reference level.
实验室测量了在英国学校使用的 Wi-Fi 设备的示例,以评估其周围的射频功率密度和总发射功率。与以前的研究不同,使用了 20 MHz 带宽信号分析仪,能够捕获和监测整个 Wi-Fi 信号。笔记本电脑的辐射模式具有一定的相似性,包括用户躯干处的最小值和穿过垂直平面将屏幕和键盘一分为二的两个最大值。最大值可能是由于安装在笔记本电脑屏幕左上角和右上角后面的独立天线产生的。接入点的模式更加对称,在给定距离处的功率密度通常更高。在 2.45 GHz 频段的 15 台笔记本电脑中,球形积分辐射功率 (IRP) 范围为 5 至 17 mW,在 5 GHz 频段的 8 台笔记本电脑中,IRP 范围为 1 至 16 mW。出于实际原因,并且由于接入点通常通过墙壁安装,其波束指向房间,因此它们的功率在半球面上进行了积分。在 2.4 GHz 频段的 12 个接入点中,功率范围为 3 至 28 mW,在 5 GHz 频段的 6 个接入点中,功率范围为 3 至 29 mW。除了球形 IRP 测量外,还在距离设备 0.5 m 及以上的距离处测量了功率密度,与低辐射功率一致,这些都远低于 ICNIRP 参考水平。