Assessment of Actual Maximum RF EMF Exposure from Radio Base Stations with Massive MIMO Antennas

Abstract

Radiofrequency (RF) electromagnetic (EMF) exposure from a massive MIMO radio base station (RBS) operating in a commercial network has been assessed by means of measurements. The impact of beamforming and the influence of traffic variation on the exposure levels were evaluated by means of network based measurements in addition to field strength measurements on-site The exposure was found to be much below the value obtained assuming constant maximum power transmission in a fixed beam direction (i.e., the theoretical maximum exposure) None of the time-averaged exposure values measured on-site was found to be larger than 6% of the theoretical maximum. These experimental data confirms that, the output power from massive MIMO base stations is spatially distributed and that assuming constant peak power transmission in a fixed direction leads to unrealistic exposure values.