閉空間生活環境におけるRF-EMCの総括

摘要

電車，航空機，エレベータなどの導体壁で囲まれた閉空間内部では，携帯電話等のRF電波は自由空間とは異なる閉空間固有の特殊な電磁界を形成する.これらの閉空間は生活環境の一部であり，そのような内部電磁界が関わる人体防護並びに植込み型医療機器EMIのEMC問題を慎重に評価することが重要である.しかし，マイク口波のようなRF電波に関わる電磁界解析や人体內SAR·植込み型医療機器EMI評価を正確に行うことは解析モデルが複雑化して容易ではない.解析の簡略化のため近似的に人体の存在を無視した無損失空間を仮定すると内部電磁界を過大評価する問題が起きる[1].正確な評価のため，携帯電話保持者を含む人体の存在するモデル化が必要である.本講演は，筆者が関わってきた高精度電磁界数値シミュレーション[2],実験測定[2],極限的無限反射仮説に基づくEMF近似[3],人体のEMC評価[2],[4]及び関連する社会動向等を取り纏めて総括する.%Inside of closed areas surrounded by conductive walls, e.g., train carriages, airplanes or elevators, the RF wave transmitted from mobile phone creates a peculiar EMF distribution to the closed area different from in the free space. Since those areas are a part of the living environment, it is important to carefully assess the EMC safety issues related to the exposure guidelines and the implantable medical devices EMI. However, it is not easy to correctly analyze EMF distribution and estimate SARs or EMIs regarding internal human body for microwave RF waves due to the analysis model complexity. An assumption of approximated loss free condition ignoring the existence of human bodies causes fatal over estimations [1]. Hence, it is necessary for accurate analyses and estimations to include the human bodies of mobile phone user and other passengers in modeling. This special lecture summarizes the study results of precise numerical simulations of EMF[2], experimental measurements[2], an EMF approximation based on an ultimate endless reflection hypothesis[3], and EMC evaluations on human body[2],[4] which this lecturer directed concerning some typical closed areas, and related social issues.