Human Exposure Assessment in Indoor Environments Using A 60 GHz Personal Exposure Meter

International audienceSHORT ABSTRACT This paper presents the first mm-wave personal exposure meter (mm-PEM) to assess human exposure to the 5th generation of mobile networks (5G) in indoor environments. The mm-PEM consists of 9 elements of an antenna array and is calibrated on a skin-equivalent phantom in a reverberation chamber at 60 GHz. The designed mm-PEM has a response of 1.043 (0.17 dB) at 60 GHz which is very close to the desired response of a PEM i.e. 1 (0 dB). The mm-PEM measured an incident power density of 41 mW.m-2 at 60 GHz for an input power of 1 mW in the empty chamber. INTRODUCTION The rapid progress in 60-GHz wireless technologies and the availability of the 5th generation of mobile networks (5G) in the near future [1] has raised concerns regarding the potential adverse health effects of mm-waves on human body. The absorption of mm-waves is limited to skin tissues [1]. Therefore, the incident power density (IPD) is studied as a dosimetric quantity. The safety limits of IPD are 1 mW.cm-2 and 5 mW.cm-2 averaged over 20 cm 2 of the exposed area for general public and occupational exposure, respectively [2]. Human exposure to radiofrequency (RF) electromagnetic fields is usually measured by Personal Exposimeters (PEMs) [3, 4]. These are portable devices worn on body allowing for continuous measurement of the electric fields strength in several frequency bands for which protocols have been developed [5]. PEMs are calibrated in free space while used on body. In other words, the measured values are compromised by the presence of the human body and thus have large measurement uncertainties [6]. In order to reduce this measurement uncertainty, personal distributed exposimeters (PDE) with multiple antennas can be used for single [7] and multi telecommunication bands [8]. Research shows that people spend more than 80% of their times indoors [9]. This could increase human exposure the electromagnetic fields. The total power in an indoor environment consists of specular and diffuse multipath components. The former and the latter are due to the reflections from large surfaces and presence of objects in a room, respectively. The DMC can contribute up to 95% to the total power density in an indoor environment [10]