Facing Challenges in Zero-Span Measurements of 5G mm-Wave EMF Power in LoS and NLoS Propagation

We present a methodology for on-site zero-span (ZS) measurement of incident power generated by 5G base stations (BSs) that operate at millimeter-waves (mm-waves), analyzing the challenges offered by the new frequency band and nonline-of-sight (NLoS) propagation, which is the most common situation for mobile network users. We also investigate the impact of omnidirectional and directional measurement antennas. This is the first research on this topic available in scientific literature. Our results reveal that the measurement method designed for frequencies below 6 GHz in line-of-sight (LoS) conditions is also applicable in the mm-wave range. At the same time, in NLoS, mitigation strategies are suggested to measure signals accurately. That is, an omnidirectional antenna is recommended since a directional one requires an initial assessment to align the probe with the direction of the strongest signal. In addition, directional antennas under NLoS conditions do not guarantee that the power density coming from different directions due to reflections is measured entirely. This study holds significant importance for international standardization bodies focusing on establishing measurement methods to evaluate exposure originating from mobile network BSs.