# RF-EMF Exposure near 5G NR Small Cells
## 3 Results  
The three types of exposure levels obtained directly from the measurements (the extrapolated worst-case \(E_{max}\), and the time-averaged \(E_{avg,min}\) and \(E_{avg,max}\)) are shown in Figure 3 for both sites as a function of distance to the base station. In total, with the SRM setup, measurements were performed at 30 positions at horizontal distances from the base station ranging from 0.5 m to 100 m, all at 1.5 m above the ground or floor (three positions were performed on the flat roof of the second site), and with the FSV at 12 positions at horizontal distances between 0.9 m and 10 m, with the probe on a telescopic pole placed at a height between 2.2 m to 5.5 m. Most of the measurements were within the scanning range of the base station radio. Those that were not (indicated by grey markers in Figure 3), were either too close to the base station (horizontally) so they were below the main lobe of the radiation pattern, or too far to the sides of the radiation pattern. First of all, the results of the FSV and SRM measurement setups were visibly in line with each other. This was observed most clearly at site #2, where there was an overlap in the distances at which measurements were taken. Hence, the measurement results of the two setups were treated as equivalent. Furthermore, it is observed that the exposure levels at positions outside the scanning range (e.g., below the antenna) were 25-100 times lower than those within the scanning range at the same distance (Figure 3). In Figure 4, the theoretical maximum exposure levels \(E_{max}\) obtained at the two sites were scaled to the respective small-cell powers, i.e., to an EIRP of 50 dBm for site #2 (E100 microcell) and to a transmit power of 30 dBm for site #1 (AAS small cell). Between the two sites, the exposure levels are very similar, especially at distances above 5 m. However, closer to the base station, the scaled levels at site #2 were higher, despite the lower EIRP. The flatter log(distance)-log(electric-field strength) curve of site #1 at short distances may be due to the more extensive radiating near-field region of its larger AAS (up to \(\sim\)20 m). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Variable** & **Site \#1** & **Site \#2** \\ \hline Number of active users & 10 & 10 \\ Typical usage (connection time) & 10 s & 10 s \\ Number of antenna elements & 100 & 4 \\ MaMIMO/beamforming scheme & Codebook ‘grid of beams’ & n/a \\ \(DC_{site,95}\) & 0.20 & 0.96 \\ \hline \hline \end{tabular} n/a = not applicable.  
\end{table} 
Table 3: Assumptions made in the calculation of the spatiotemporal duty cycles at the two 5G new radio (NR) sites considered in this study [19]. Figure 4: Theoretical maximum exposure levels \(E_{\text{max}}\) (in V/m) obtained at two sites with a 5G new radio (NR) base station—scaled to small-cell powers [2; 3]—as a function of the distance to the antenna. Only positions within the scanning range of the base station radio are featured here. Maximum permissible exposure (MPE) limits issued by ICNIRP [17] are indicated by the blue dashed line (occupational) and the magenta dotted line (general public). The red dashed line indicates the boundary between occupational (<1 m) and general public exposure (>1 m) (see \(D_{m}\) for E100 in Table 1). Figure 3: Three types of electric-field levels (\(E_{\text{avg},min}\) as rings, \(E_{\text{avg},max}\) as circles, and \(E_{\text{max}}\) as pentagons; all in V/m) measured at two sites with a 5G new radio (NR) base station as a function of the distance to the antenna with two types of measurement equipment, namely an FSV setup (green markers) and an SRM setup (orange markers) (markers in grey denote measurements outside the scanning range of the base station radio and were added for completeness rather than direct comparison). Maximum permissible exposure (MPE) limits issued by ICNIRP [17] are indicated by the blue dashed line (occupational) and the magenta dotted line (general public).