Whole-Body Exposure System Using Horn Antennas With Dielectric Lens at 28 GHz

In the revised international guidelines and standard for human protection from electromagnetic fields, the permissible specific absorption rate (SAR) for whole-body exposure has been extended from 3 or 10 GHz to 300 GHz. The rationale for this revision is the extrapolation from findings of conventional radio-frequency exposure and infrared radiation. However, experiments of whole-body exposure in human subjects are limited to a few studies, which were conducted below 6 GHz. In this study, an exposure system at 28 GHz targeting a wide area of the human back was developed, which consists of two horn antennas with a dielectric lens. The effectiveness of the proposed exposure system was evaluated by computational dosimetry and experiments. The computed power absorption and measured distributions in the wave absorber and the back of the human subject were in good agreement. Under the compliance with the local exposure limits, the whole-body average SAR was 0.35 W/kg, which is comparable to the limit for whole-body exposure of 0.4 W/kg for occupational exposure in the international guidelines and standard. The developed exposure system would be useful to evaluate the thermophysiological response to whole-body exposure above 6 GHz.