摘要
近年来,随着电信业和移动通信的迅速发展,手机已由过去的奢侈品成为大众消费品。截止2012年6月底,中国手机用户数已达到10.52亿户。预计2012年手机用户数量有望突破11亿。伴随着用户数量的增加,国内各大运营商不断完善自己的手机基站覆盖网络,特别是近年来3G、以及即将商用的LTE网络的推广,基站的建设更是掀起了新一轮的高潮。因此,人们对手机及基站电磁辐射对人体健康的影响的关注度也逐渐增加。
电磁辐射对人体的影响是一个涉及面广泛的课题,应该通过多方面诸如生物医学、电磁场理论、电磁边值问题等知识系统考虑。电磁辐射与人体相互作用的研究是一个复杂的过程。但是我们可以明确的是,无论从现实意义,还是其广阔的应用前景的角度考虑,研究手机对人体头部的影响都很有价值。首先,可以通过实验测量将得到的有关剂量与当前国际应用更为广泛的电磁辐射卫生相关标准进行切实的比较,为评估手机电磁辐射和建立符合我国国情的电磁辐射卫生标准提供准确的参考数据;其次,可以给更高端的手机设计提供研究方向,依据人头对手机天线方向图的影响;最后,可以根据辐射剂量在人体局部位置的大小,找出使用手机的最佳方式,从而有效降低人体对手机电磁辐射的吸收。
本文的研究内容和成果如下:
(1)在阅读大量最新国内外相关资料文献的基础上,对本课题手机电磁辐射研究背景及目前国内外普遍使用的有关SAR值标准进行了总结。
(2)对与本课题有关的理论知识进行了介绍,包括:电磁辐射的相关原理、电磁场场区划分、生物电磁学、电磁学的生物效应以及生物电磁剂量学量SAR。
(3)在简单介绍常用电磁仿真算法的基础上,着重阐述了与本文仿真相关的有限元法,包括有限元法的发展、基本原理、方程的求解推导、自适应网格的剖分以及基于有限元法的电磁仿真软件HFSS的介绍。
(4)利用实验室设备DASY5,进行了手机SAR的头部和身体部分的测量,并根据身体部分的测量结果及分析,提出在身体部分使用手机时,在减小手机辐射方面,尽量使用有线耳机,而尽量不使用免提这一观点。
(5)基于有限元法,利用HFSS建立了手机外壳、双频PIFA天线及人头模型,并进行手机与人头相互作用的仿真及实验对比。最后提出了在减小手机电磁辐射方面,一些可以人为减小和技术方面的改进措施。
In recent years, with the rapid development of the telecommunications industry and mobile communications, the luxury phone in the past has been become mass consumer goods. As of the end of June2012, the number of mobile phone users in China has reached1.052billion. It's expected that in the end of2012the number of users is expected to exceed1.1billion. Along with the increase in the number of users, the major domestic operators constantly improve the network coverage of the mobile phone base stations. Especially in recent years,3G, as well as the promotion of the upcoming commercial LTE network, the construction of base stations set off a new round of high tide. Therefore, the attention of the people on the mobile phone and base station electromagnetic radiation on human health is also increasing.
The impact of electromagnetic radiation on the human body is a wide range of topic, the problem needs to be comprehensive and cross-use of the electromagnetic field theory, electromagnetic boundary value problem, biomedical, and antenna theory of knowledge. Thus, electromagnetic radiation interacts with the human body is a complex process. At the same time, studies the impact of the mobile phones of people head will have important practical significance and broad application prospects. First, by predicting the mobile phone the electromagnetic radiation doses on the human body, with a variety of electromagnetic radiation hygiene standards directly compare, provide the basis for the evaluation of current mobile phone radiation is in line with the existing health standards, in line with China's actual radiation hygiene standards to establish provide valuable information data; Second, we can provide the location and distribution of the theoretical results, the best way to find phone operating mobile phone radiation by the greatest harm to the human body, reduce the damage to mobile phone radiation on the human body; Finally, through the head of the mobile phone direction diagrams of direction can be provided for the new phone.
Content and results of this research are as follows:
(1) On the basis of a lot of reading related literature, the research background of mobile phone electromagnetic radiation and generally used SAR standard were summarized. On this basis, the research idea that mainly experimental measurements and supplemented by simulation was proposed.
(2) The theoretical knowledge related to the topic was described, including the principle of electromagnetic radiation, Bioelectromagnetics, biological effects of electromagnetism and bio-electromagnetic dosimetry amount of SAR.
(3) Finite element method which related to this article simulation was highlighted, including the development of the finite element method, the basic principle, derivation of equations, adaptive split of the grid and the introduction of electromagnetic simulation software HFSS based on the finite element method, after briefly introducing commonly used electromagnetic simulation algorithm.
(4) The measurement of the head and body parts of the phone SAR was finished by utilizing the laboratory equipment DASY5. And according to the measurement results and analysis of the part of the body, the part of the body when using a mobile phone, reduce cell phone radiation, try to use a wired headset, and try not to use hands-free this view.
(5) The models of cell phone shell, a dual-band PIFA and human head were established by using HFSS based on the finite element method. Interaction on the phone with the head of the simulation and experimental comparison. Finally, to reduce mobile phone electromagnetic radiation, artificially reduced and technology improvements were proposed.
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