Carrasco Eduardo, Colombi Davide, Foster Kenneth R, Ziskin Marvin, Balzano Quirino
Universidad Politécnica de Madrid, Madrid, Spain.
Ericsson AB, Torshamnsgatan 21, Stockholm, Sweden.
Radiat Prot Dosimetry. 2019 Jun 1;183(4):488-495. doi: 10.1093/rpd/ncy177.
The emerging 5 G wireless devices working at frequencies above 6 GHz are expected to have antenna arrays formed by dipoles, slots, patches or their combination. At lower frequencies, the accepted criteria for exposure compliance is stated in terms of specific absorption rate. IEEE and ICNIRP are adopting epithelial or transmitted power density (PD through body surface) as the dosimetric reference for frequencies above 6 GHz, which entails the measurement of free space PD. Theoretical and numerical results presented in this article show that it is possible to perform meaningful free space PD assessments at half wave (λ/2) distance from arrays and, with the proper instrumentation, as close as λ/(2π). However, if a dissipative body is placed very close (<λ/2π) to the arrays, its reflection and absorption of RF energy can change the electric currents and charges over the antenna. The relevance of such an effect should be further investigated, for instance by means of experimental analysis including measurements of tissue heating when in the presence of a strong reactive near field.
预计工作在6GHz以上频率的新兴5G无线设备将具有由偶极子、缝隙、贴片或它们的组合形成的天线阵列。在较低频率下，暴露合规的公认标准是以比吸收率来表述的。对于6GHz以上的频率，IEEE和国际非电离辐射防护委员会（ICNIRP）采用上皮或传输功率密度（通过体表的功率密度）作为剂量学参考，这需要测量自由空间功率密度。本文给出的理论和数值结果表明，在距阵列半波（λ/2）距离处，使用适当的仪器，甚至在λ/（2π）的近距离内，都可以进行有意义的自由空间功率密度评估。然而，如果一个耗散体放置在非常靠近阵列（<λ/2π）的位置，其对射频能量的反射和吸收会改变天线上的电流和电荷。这种效应的相关性应进一步研究，例如通过实验分析，包括在强反应性近场存在时测量组织加热情况。
