Experimental evaluation of RF-EMF emitted by electronic devices of IoT systems and comparison with other wireless technologies

Our paper presents a study of an environmental sensing system operating at 868 MHz, based on LoRa technology, the physical layer of the LoRaWAN. We utilized LoRa technology to monitor basic environmental parameters in various workplaces and to evaluate personal exposure to radiofrequency electromagnetic fields (RF-EMF) from IoT devices. The experimental campaign followed the IEC 62232:2017 standard, measuring the power density of electromagnetic fields in specific microenvironments. Our measurements show that LoRa technology has lower values than traditional Wi-Fi and cellular wireless systems. In the LoRaWAN band, the highest temporal variation of average power density fluctuated between 81.4 µW/m2 and 1320 µW/ m2, while maximal values were 1893 µW/m2. Also, the cumulative distribution function fits with the lognormal distribution. We found that the power density values of RF-EMF emitted from LoRa technology comply with national and international guidelines for sensitive indoor microenvironments. Furthermore, increasing the usage of environmental sensing systems is not expected to affect the overall RF-EMF radiation levels soon.