The most recent safety guidelines define basic restrictions for electromagnetic field exposure at frequencies more than 6 GHz in terms of spatial‐ and time‐averaged transmitted power density inside the body. To enable easy‐to‐perform evaluations in situ, the reference levels for the incident power density were derived. In this study, we examined whether compliance with the reference levels always ensures compliance with basic restrictions. This was evaluated at several distances from different antennas (dipole, loop, slot, patch, and helix). Three power density definitions based on integration of the perpendicular real part of the Poynting vector, the real part of its three vector components, and its modulus were compared for averaging areas of λ ²/16, 4 cm² (below 30 GHz) and 1 cm² (30 GHz). In the reactive near‐field (d  < λ /(2π )), the transmitted power density can be underestimated if an antenna operates at the free space exposure limit. This underestimation may exceed 6 dB (4.0 times) and depends on the field source due to different coupling mechanisms. It is frequency‐dependent for fixed‐size averaging areas (4 and 1 cm²). At larger distances, transmission can be larger than the theoretical plane‐wave transmission coefficient due to backscattering between the body and field source. Using the modulus of the incident Poynting vector yields the smallest underestimation. © 2020 Bioelectromagnetics Society.

中文翻译：

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入射功率密度的局限性作为感应电磁场的替代。

最新的安全指南根据人体内部的空间和时间平均发射功率密度，定义了超过6 GHz频率的电磁场暴露的基本限制。为了便于现场进行评估，得出了入射功率密度的参考水平。在这项研究中，我们检查了是否遵守参考水平始终可以确保遵守基本限制。在距不同天线（偶极子，环路，缝隙，贴片和螺旋线）的几个距离处进行了评估。基于坡印廷矢量的垂直实部的集成三个功率密度定义，它的三个矢量分量的实数部分，而其模量的平均值的区域进行比较λ ² /16，4厘米²（低于30 GHz）和1 cm ²（30 GHz）。在反应性近场（d  <  λ /（2 π）），发射功率密度可以如果天线在自由空间的暴露极限进行操作低估。这种低估可能会超过6 dB（4.0倍），并且由于耦合机制不同而取决于场源。对于固定大小的平均面积（4和1 cm ²），它与频率有关。在较远的距离处，由于身体和场源之间的反向散射，传输可能会比理论平面波传输系数大。使用入射坡印廷矢量的模量得出最小的低估。©2020生物电磁学会。