| As the research on 5G mobile communication technology is being carried out closely around the world,5G has become a hotspot for the development of the communication industry.China's 5G mobile communication has begun commercial use and is expected to be popular in 2020.The use of 5G mobile phones will increase rapidly,causing public concern about whether the electromagnetic environment of 5G mobile phones will pose a threat to human health.This thesis uses electromagnetic dosimetry to simulate and study the electromagnetic exposure of the 5G mobile phone antenna to the human head,combined with the electromagnetic exposure safety protection guide established by the International Commission on Non-Ionizing Radiation Protection Then conduct a safety assessment.The specific research methods of this thesis are as follows:(1)Briefly explain the progress of 5G mobile communications,the harm of electromagnetic exposure to human body,and the current research status of mobile phone electromagnetic exposure at home and abroad.Introduced the concept of Specific Absorption Rate(SAR);researched and compared the relevant standards on electromagnetic exposure SAR value of mobile phones at home and abroad;introduced the basic principles of finite element numerical calculation of modern electromagnetic field theory,and passed verification analysis to study 5G Provide reliable basis for electromagnetic exposure of mobile phones.(2)Combining the characteristics of 5G mobile communication and the development trend of 5G mobile communication antennas,the main research is from multi-band miniaturized antennas,and the use of software HFSS(High Frequency Structure Simulator)based on the finite element method to establish two 5G multi-band miniaturization Mobile phone antennas are as follows: multi-band miniaturized Monopole folding antenna,its working frequency band is 765MHz-1020 MHz,1550MHz-3850 MHz and 4400MHz-4500MHz;the same designed multi-band miniaturized Monopole planar antenna,its working frequency band is 490MHz-978 MHz,1600MHz-2700 MHz,3105MHz-3972 MHz,4845MHz-5378 MHz and 5675MHz-5885MHz;can cover all frequency bands required for GSM,WCDMA,UMTS,LTE,5G communication.(3)Use HFSS software to build a three-dimensional ball head model,and calculate the relative permittivity and conductivity of human scalp,skull,and brain tissue through the fourth-order Cole-Cole model;and conduct electromagnetic exposure simulation studies of 5G mobile phone antennas,The results and distribution of the induced electric field strength and specific absorption rate of the scalp,skull,and brain at the operating frequencies of 2600 MHz and 3500 MHz for the two 5G mobile phone antennas were calculated in turn.Secondly,by changing the input power of the mobile phone antenna,the electromagnetic exposure of various tissues of the human head was calculated at 0.125 W,0.125 W and 1W,and the SAR values in the scalp,skull and brain tissue were calculated by simulation,and analyze and compare.At the same time,the effects of electromagnetic exposure on the tissues of the head were studied at different distances from the mobile phone to the human head.Finally,the calculated distribution of electric field and SAR in human tissue is compared with ICNIRP electromagnetic exposure safety protection standards and safety assessment.The results show that the scalp close to the antenna side of the mobile phone absorbs most of the electromagnetic field energy.The absorbed SAR value in the brain is about 0.25 times the total SAR value,and the induced electric field intensity is similar to the SAR value.As the distance between the mobile phone antenna and the brain area increases,the SAR value decreases accordingly.The SAR value in the brain is about 0.125 times of the scalp part,which is compared with the limit set by ICNIRP and is lower than the public electromagnetic exposure the limit value is 2W/kg,all in line with international standards.And compared with the current research results of relevant literature,it can be seen that the electromagnetic field exposure research results of these two 5G mobile phone antennas are lower and the radiation is smaller.The above work provides data reference for the formulation of China's mobile communication terminal electromagnetic exposure standards to a certain extent,and has certain application value. |
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