The system analysis of specific absorption rate(SAR)in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works.The objectives of ...The system analysis of specific absorption rate(SAR)in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works.The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station.The paper investigates the electromagnetic wave absorption inside a human body.The human body has been identified using dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna(BSA)has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance(R)of human body from BSA is varied in the range of 0.1 m to 5.0 m.For the number of carrier frequency equal to one and R=0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies.Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.展开更多
目的通过对SAR影响参数研究,计算10秒SAR,指导MR扫描顺利进行。方法采用GE公司HD3T扫描仪,头颅8通道线圈,扫描序列为T2-FSE,改变体重、TR、层数等参数对水模进行扫描,观察SAR的改变。结果SAR与体重和TR有关,而与扫描的层数无关,SAR是RF...目的通过对SAR影响参数研究,计算10秒SAR,指导MR扫描顺利进行。方法采用GE公司HD3T扫描仪,头颅8通道线圈,扫描序列为T2-FSE,改变体重、TR、层数等参数对水模进行扫描,观察SAR的改变。结果SAR与体重和TR有关,而与扫描的层数无关,SAR是RF、B0、体重和TR的函数。根据体重与10秒SAR的关系曲线,通过MATLAB,进行一个曲线拟合,得出10 s SAR与体重的关系方程式:SAR=((-5.96E-09)X4-(2.08E-06)X3+0.0005681X2-0.04531X+1.638)*Peak_SAR.结论SAR是RF脉冲序列、B0、体重和TR的函数,我们所得到的MATLAB4次方程式,只要输入病人体重和Peak_SAR就能直接得到10 s SAR,就可以估计扫描是否暂停,以及暂停时间。展开更多
SAR(Specific Absorption Rate)通常称为吸收比值或吸收比率,是指移动终端电磁波能量吸收比值。目前国际通用的标准有两个,一个是欧洲标准(CE)每10克小于2.0w/kg,一个是美国标准(FCC)每克小于1.6mw/g。移动终端的SAR与TRP(Total Radio P...SAR(Specific Absorption Rate)通常称为吸收比值或吸收比率,是指移动终端电磁波能量吸收比值。目前国际通用的标准有两个,一个是欧洲标准(CE)每10克小于2.0w/kg,一个是美国标准(FCC)每克小于1.6mw/g。移动终端的SAR与TRP(Total Radio Power总辐射功率)这一相互制约的关系成了目前移动终端在保证高要求的发射功率条件下有低SAR值的难题。一般的降SAR方式为在主板上的热点处贴吸波材料,但是这有碍于终端的结构设计,并且成本较高,可靠性不佳。本论文通过天线本体设计来改变移动终端的主板上的电流分布,在保证总电流强度不减小的情况下通过降低主板上的电流峰值来降低SAR值。大大节省了降SAR成本。具有较高的推广性和可实现性。展开更多
Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues...Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.展开更多
基金This work is collaborative research with the Department of Electronics&Communication Engineering,Acharya Institute of Technology,Bengaluru,India.And also this work is a collaborative research between Yangon Technological University and University of Oulu in Finland based on the enhancement of Telecommunication Engineering Education in YTU.This work is fully supported by the government research funds of 2020-2021 academic year which is the grant no of GB/D(4)2020/4.
文摘The system analysis of specific absorption rate(SAR)in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works.The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station.The paper investigates the electromagnetic wave absorption inside a human body.The human body has been identified using dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna(BSA)has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance(R)of human body from BSA is varied in the range of 0.1 m to 5.0 m.For the number of carrier frequency equal to one and R=0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies.Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.
文摘目的通过对SAR影响参数研究,计算10秒SAR,指导MR扫描顺利进行。方法采用GE公司HD3T扫描仪,头颅8通道线圈,扫描序列为T2-FSE,改变体重、TR、层数等参数对水模进行扫描,观察SAR的改变。结果SAR与体重和TR有关,而与扫描的层数无关,SAR是RF、B0、体重和TR的函数。根据体重与10秒SAR的关系曲线,通过MATLAB,进行一个曲线拟合,得出10 s SAR与体重的关系方程式:SAR=((-5.96E-09)X4-(2.08E-06)X3+0.0005681X2-0.04531X+1.638)*Peak_SAR.结论SAR是RF脉冲序列、B0、体重和TR的函数,我们所得到的MATLAB4次方程式,只要输入病人体重和Peak_SAR就能直接得到10 s SAR,就可以估计扫描是否暂停,以及暂停时间。
文摘SAR(Specific Absorption Rate)通常称为吸收比值或吸收比率,是指移动终端电磁波能量吸收比值。目前国际通用的标准有两个,一个是欧洲标准(CE)每10克小于2.0w/kg,一个是美国标准(FCC)每克小于1.6mw/g。移动终端的SAR与TRP(Total Radio Power总辐射功率)这一相互制约的关系成了目前移动终端在保证高要求的发射功率条件下有低SAR值的难题。一般的降SAR方式为在主板上的热点处贴吸波材料,但是这有碍于终端的结构设计,并且成本较高,可靠性不佳。本论文通过天线本体设计来改变移动终端的主板上的电流分布,在保证总电流强度不减小的情况下通过降低主板上的电流峰值来降低SAR值。大大节省了降SAR成本。具有较高的推广性和可实现性。
基金This study was supported by the National Natural Science Foundation of China(Nos.62022037,61775028,81571722,61528401 and 61921002)Guangdong province(2019ZT08Y191)+1 种基金Shenzhen Science and Technology Program(KQTD20190929172743294)Startup grant from Southern University of Science and Technology.
文摘Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.
