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在65兆赫兹至2吉赫兹之间,对诺曼人体体素模型中半波偶极天线的场进行空间平均并进行相应的比吸收率计算。

Spatial averaging of fields from half-wave dipole antennas and corresponding SAR calculations in the NORMAN human voxel model between 65 MHz and 2 GHz.

作者信息

Findlay R P, Dimbylow P J

机构信息

Radiation Protection Division, Health Protection Agency, Chilton, Didcot. OX11 0RQ, UK.

出版信息

Phys Med Biol. 2009 Apr 21;54(8):2437-47. doi: 10.1088/0031-9155/54/8/012. Epub 2009 Apr 1.

Abstract

If an antenna is located close to a person, the electric and magnetic fields produced by the antenna will vary in the region occupied by the human body. To obtain a mean value of the field for comparison with reference levels, the Institute of Electrical and Electronic Engineers (IEEE) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) recommend spatially averaging the squares of the field strength over the height the body. This study attempts to assess the validity and accuracy of spatial averaging when used for half-wave dipoles at frequencies between 65 MHz and 2 GHz and distances of lambda/2, lambda/4 and lambda/8 from the body. The differences between mean electric field values calculated using ten field measurements and that of the true averaged value were approximately 15% in the 600 MHz to 2 GHz range. The results presented suggest that the use of modern survey equipment, which takes hundreds rather than tens of measurements, is advisable to arrive at a sufficiently accurate mean field value. Whole-body averaged and peak localized SAR values, normalized to calculated spatially averaged fields, were calculated for the NORMAN voxel phantom. It was found that the reference levels were conservative for all whole-body SAR values, but not for localized SAR, particularly in the 1-2 GHz region when the dipole was positioned very close to the body. However, if the maximum field is used for normalization of calculated SAR as opposed to the lower spatially averaged value, the reference levels provide a conservative estimate of the localized SAR basic restriction for all frequencies studied.

摘要

如果天线靠近人体放置,天线产生的电场和磁场会在人体占据的区域内发生变化。为了获得场的平均值以便与参考水平进行比较,电气和电子工程师协会(IEEE)以及国际非电离辐射防护委员会(ICNIRP)建议在人体高度范围内对场强的平方进行空间平均。本研究旨在评估在65MHz至2GHz频率范围内,半波偶极子与人体距离为λ/2、λ/4和λ/8时,空间平均法的有效性和准确性。在600MHz至2GHz范围内,使用十次场测量计算得到的平均电场值与真实平均值之间的差异约为15%。研究结果表明,使用现代测量设备(进行数百次而非数十次测量)有助于获得足够准确的平均场值。针对NORMAN体素模型计算了归一化到计算得到的空间平均场的全身平均比吸收率(SAR)值和峰值局部SAR值。结果发现,对于所有全身SAR值,参考水平较为保守,但对于局部SAR并非如此,特别是在1 - 2GHz区域,当偶极子非常靠近人体放置时。然而,如果使用最大场而非较低的空间平均值对计算得到的SAR进行归一化,参考水平为所有研究频率下的局部SAR基本限制提供了保守估计。

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