行動電話對人體頭部產生之電磁能量特定吸收率及溫度上升之研究

Computation of SARs and Temperature Increase in Human Head Models Exposed to Cellular Phones

楊漢鵬(Han-Peng Yang)

指導教授 ： 陳興義

元智大學/工程學院/通訊工程學系/碩士(2004年)

摘要

本論文利用時域有限差分法 (FDTD) 來研究球體、正立方體、粗糙與真實人體頭部模型受到行動電話輻射在900與1800 MHz時所感應之電磁能量特定吸收率 (SAR)。行動電話採用五種模型，包括耦極天線、金屬材料手機模型、介質材料手機模型、等效材料手機模型與中空型手機模型。研究結果發現人體頭部所感應的SAR值受到很多不確定因素之影響，包括人頭外型、頭部組織之電特性常數、手吸收功率之影響、行動電話之模型、均勻與不均勻頭部模型、手機之材料…等。我們在得到人體頭部內之SAR值之後，再使用熱轉換方程式估算真實人頭模型的溫度上升值。熱轉換方程式與SAR的最大值有密切關係並且在使用時需加上邊界條件求解之。從真實人體頭部模型的溫度上升值中發現到，溫度會在最先的10分鐘之內急速上升，之後溫度上升速率便慢了下來並且會在20分鐘後達到穩定值，而其溫度的上升值遠小於達到傷害腦丘或神經元的溫度上升臨界值。我們所得到的結果是，在腦之溫度上升值可能是安全的不會造成生理上的傷害。

關鍵字

時域有限差分法 ； 電磁能量特定吸收率 ； 熱轉換方程式 ； 真實人頭模型的溫度上升值

並列摘要

In this thesis, the Finite-Difference Time-Domain (FDTD) method is used to investigate the specific absorption rate (SAR) induced in spherical, cubical, coarse, and realistic human head models exposed to a cellular phone at 900 and 1800 MHz. The cellular phone is modeled by five handset models including dipole antenna, metallic handset, dielectric handset, equivalent handset, and hollow handset. It is found that SARs induced in the human head are affected by many uncertainty factors including head shapes, electric properties of human head tissues, hand absorption power effect, cellular phone models, homogeneous and inhomogeneous head models, cellular phone materials, …etc.. After obtaining the SAR values inside the human head, the temperature increase in the realistic human head model is determined by solving a bioheat equation correlated to the peak SAR value and constrained to a boundary condition. From the results of temperature increase in the realistic human head model, it is found that the temperature increase rapidly over the first 10 min, and the rate of temperature rise then slows down and the steady state is achieved after 20 min of exposure. It is also found that the temperature increase is much smaller than the temperature-rise threshold for the hypothalamus or the neuron damage. The obtained result of temperature increase in the brain may be allowable without physiological damage.

並列關鍵字

Finite-Difference Time-Domain ； specific absorption rate ； bioheat equation ； temperature increase in the realistic human head model

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