手机辐射与人体头颅相互作用的仿真分析

The Simulation Analysis of the Interaction between Human Head and Radiation of Cell Phone

手机与人体相互作用中涉及两方面问题,一是人体吸收的电磁剂量是否超过限值标准从而对人体造成伤害;二是人体对手机的辐射特性会产生什么影响。采用时域有限差分(FDTD)法经数值仿真进行探讨。结果表明,当手机内置PIFA天线、辐射频率为1 800 MHz、辐射功率为1 W时,人体头颅的总体平均比吸收率未超过ICNIRP颁布的公众基本限值标准,但头颅内任意10 g组织中平均比吸收率的最大值却超过了公众基本限值标准。同时,头颅的影响使手机的辐射特性发生变化,当手机贴于左耳时,手机天线的方向图较之于处在自由空间时的方向图而言发生了向上、向左的偏斜,并且辐射到空间的功率约为辐射总功率的60%,被头颅吸收的功率约为辐射总功率的40%。

The interaction between human and radiation of cell phone involves two problems. One is whether the bioelectromagnetic dose absorbed by human body is beyond the standard limit, the other is what effects the body will have on the radiation of cell phone. Simulation analysis were conducted based on finite difference time domain （FDTD）. Because the distance between the head and cell phone is much smaller than the wavelength of electromagnetic waves radiated by celt phone, the interaction could be regarded as a near-field problem in which the head and cell phone were considered as an inseparable whole. At the condition of in-phone PIFA antennas, 1 800 MHz radiation frequency and 1 W radiation power, simulation analysis showed that the average specific absorption rate overall head did not exceed the ICNIRP public promulgation of the basic limit, but the maximum of average specific absorption rate in arbitrary 10 g tissue in the head was more than the basic limit. At the same time, the radiation characteristics of the phone was changed by the influence from the head. When the phone affixed to the left ear, the pattern of the phone antenna was slanted to the left and upward compared with that the phone was in the free space. The power radiated to space was about 60 % of total radiation power and the power absorbed by the head was about 40 % of total radiation power.