Hybrid Analysis of Human Exposure from Base-Station Antennas in Underground Environment

Jianqing WANG  Masayuki KOMATSU  Osamu FUJIWARA  Shinji UEBAYASHI  

Publication
IEICE TRANSACTIONS on Communications   Vol.E89-B   No.12   pp.3411-3416
Publication Date: 2006/12/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.12.3411
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility(EMC)
Keyword: 
underground environment,  base station antenna,  SAR,  ray-tracing method,  FDTD method,  safety evaluation,  

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Summary: 
In this study we have employed an effective technique for dosimetric analyses of base station antennas in an underground environment. The technique combines a ray-tracing method and the finite-difference time-domain (FDTD) method to calculate the specific absorption rate (SAR) in the human body. The ray-tracing method was applied to evaluate the incident fields in relation to the exposed subject in a three-dimensional space, while the FDTD method was used to calculate the detailed SAR distributions in the human body. A scenario under an underground passage with the installation of a top-loaded monopole antenna was analyzed to investigate the relationship between the actual antenna exposure and a plane-wave exposure. The results show that the plane-wave exposure overestimated the whole-body average SAR in most cases, although this was not always true for peak SAR. The finding implies not only the usefulness of the present uniform-exposure-based reference level for the whole-body average SAR evaluation but also the necessity of modeling actual underground environment for high-precision local peak SAR evaluation.