人體通訊引起身體的電磁波能量特定吸收率與溫升之研究

SAR and Temperature Increase in Human Bodies Due to On-Body Communications

李恆銘(Heng-Ming Li)

指導教授 ： 陳興義

元智大學/電機通訊學院/通訊工程學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00075

摘要

本論文之研究工作主要探討人體在人體通訊系統下所產生的電磁波能量吸收與溫度上升值。研究過程中是利用時域有限差分法來計算900 MHz與2.45 GHz下人體表面在不同位置受到平板天線輻射所造成之電磁波能量特定吸收率以及溫度變化，而此人體是採用十種組織所組成的非均勻性人體模型。研究結果中發現最大電磁波能量特定吸收率發生在皮膚表面上，且平板天線與皮膚表面之相對距離增加，電磁波能量特定吸收率會劇烈地下降。在900 MHz與2.45 GHz下之最大電磁波能量特定吸收率分別為0.03 以及0.9瓦特/公斤。同樣地發現，在900 MHz與2.45 GHz下平板天線在人體表面不同位置上所造成的每層平均電磁波能量特定吸收率之最大值分別約為10-4至10-3瓦特/公斤以及10-2至10-3瓦特/公斤之間，其值皆遠小於ANSI/IEEE之電磁波能量吸收率安全規範，其安全值為人體在不可控制環境下，一公克組織器官受到電磁波輻射所產生之電磁波能量特定吸收率不可超過1.6 瓦特/公斤，或十公克組織器官之電磁波能量特定吸收率不可超過2 瓦特/公斤。而在溫度變化之研究中發現，在900 MHz下局部一克組織與十克組織的溫度上升最大值發生於左胸位置，分別為1.2?10-3℃及6.3?10-4 ℃，又2.45 GHz下，局部一克組織與十克組織的溫度上升最大值發生於心臟位置，分別為2.5?10-2℃及5?10-3 ℃。而最大溫度上升值2.5?10-2℃，其值遠低於人體內神經元在溫度高過正常體溫4.5℃，且持續超過三十分鐘將會造成永久性傷害，以及在皮膚組織層的溫度上升值至少要10℃以上之變化才會對皮膚造成傷害。

關鍵字

電磁波能量特定吸收率 ； 溫升 ； 平板天線

並列摘要

The research work focuses on electromagnetic energy absorption and temperature increase in a human model due to on-body communication systems. The specific absorption rates (SAR) and temperature increase in an inhomogeneous human model with ten types of tissues were studied by using the finite-difference time-domain (FDTD) method under the irradiation of a patch antenna located at different locations on the human body surface at 900 and 2450 MHz. From simulations results, it is found that the maximum local SAR occurs in the skin and decreases sharply as the distance increases from the skin. Maximum local SARs of 0.03 and 0.9 W/kg are obtained in the skin at 900 and 2450 MHz, respectively. It is also obtained that the highest layer-averaged SARs are in the order of 10-4~10-3 and 10-3~10-2W/kg for the patch antenna located on different locations on the human body surface at 900 and 2450 MHz, respectively, that are far below the ANSI/IEEE safety guideline of 1.6 W/kg for 1 g of tissue or 2 W/kg for 10 g of tissue in uncontrolled environments. It is also found that the maximum temperature increases of 1.2????-3 oC and 6.3???-4 oC occur in the left chest for 1 g of tissue and 10 g of tissue at 900 MHz, respectively. The maximum temperature increases of 2.5????-2 oC and 5.0???-3C occur in the heart for 1 g of tissue and 10 g of tissue at 2450 MHz, respectively. The maximum temperature increase of 2.5????-2 oC is far below the threshold temperature increase of 4.5 oC for neuron damage for more than 30 minutes and the temperature increase of 10 oC for thermal damage in the skin.

並列關鍵字

SAR ； Temperature increase ； patch antenna

參考文獻

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