## 3 Results and Discussion  
Table 1 summarizes all measurement data, i.e., from 396 area points, per frequency band. The minimum and maximum values of \(E_{f}^{j}\) and \(\lambda_{f}^{j}\), \(j=1,2,\ldots,396\), are given together with the mean, standard deviation (SD), and median value. The first remark about Table 1 is that, even the maximum value of \(\lambda_{f}^{j}\) is found well below 1, for all frequency bands except for the band of 27-879 MHz where the maximum exposure ratio is 1.25. The latter is an extreme outlier and it may attributed to an antenna located on a roof near the first primary school, in the suburb named \"Kounoupidiana\". This specific measurement corresponds to location #7 (out of 10), in the vicinity of the aforementioned school, and it was probably along the main beam of the antenna. Due to the aforementioned outlier, the maximum value of \(\Lambda_{j}\) at the last row of Table 1 is found above the reference level. In addition, Table 1 indicates that the SD of \(E_{f}^{j}\) and \(\lambda_{f}^{j}\) is high, for all frequency bands, a remark that may be \begin{table}
\begin{tabular}{c c} \hline \hline
**Frequency Range** & **E-Field Strength \(E_{lim,f}^{j}\) (V/m)** \\ \hline
1–3 kHz & 150/_f_ \\
3 kHz–1.43 MHz & 52.2 \\
1.43–10 MHz & 67.3/_f_ \\
10–400 MHz & 21.7 \\
400–2000 MHz & 1.065/_f_\({}^{1/2}\) \\
2–300 GHz & 47.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Reference level \(E_{lim,f}^{j}\) for general public exposure in the vicinity of schools, according to Greek legislation. Figure 1: Experimental setup of the RF-EMF measurements. (**a**) On-site measurement layout and (**b**) measurement data recording. attributed to the wide distribution of the sample; great SDs have been reported by other researchers, too [14]. The fact that the SD values of \(\lambda_{f}^{j}\) are greater than the corresponding mean values may be a sign that the distribution of the results is not normal; thus, the median value (as well as the related parameters, such as the interquartile range shown in Figure 2) is of greater importance than the mean value of the exposure ratio. [PERSON]'s median tests (95% confidence level) were performed in order to determine whether there exist statistically significant differences in median values of \(E_{f}^{j}\) and \(\lambda_{f}^{j}\) between urban and suburban environments; the results, per frequency band, are presented in the last column of Table 1. The latter suggests that all median values for urban and suburban environments, except for those corresponding to the 27-879 MHz band, are found to be statistically significantly different, i.e., \(p<0.05\). Thus, herein, the alternative hypothesis turns out to be true, i.e., the urban and the suburban environments may be viewed as different populations (with the exception of the 27-879 MHz band). This is a reasonable result and it is justified below. Urban areas differ significantly from the suburbs, as the radiation sources in the former are generally greater in number and placed much closer to each other, albeit the greater the number of sources, the less power they emit. In addition, there exist many more obstacles of any kind (all buildings, various constructions, reflective surfaces, etc.) in the urban than in the suburban areas; thus, a direct line-of-sight propagation path is more likely to occur in suburban than in urban environments. The aforementioned arguments are further supported by the fact that several well-known propagation models, such as Okumura-Hata, are quite different for urban and suburban environments; a difference that is expected to be imprinted in EMF measurements, too. Regarding the \(p\)-value obtained for the 27-879 MHz band, i.e., \(p>0.05\), it denotes that urban and suburban environments are not statistically significantly different for this specific frequency range. Applications of the aforementioned band include mainly broadcast radio and television, with the emitters usually located outside the cities and the suburbs.