306
Electromagnetic Fields in Biological Systems
In the study by Bernardi et al. (2000a), human exposure to the EM field radiated
by a rooftop-mounted base-station antenna operating around 900 MHz in an urban
environment was analyzed. The incident field and SAR distributions obtained in
the three typical exposure scenarios of Figure 5.26 are shown in Figures 5.27, 5.28,
and Figure 5.29, respectively. Each figure shows the distribution of the rms value of
the electric field on the vertical plane containing the antenna maximum radiation
direction in the absence of the subject and in the presence of the subject, as well as
the SAR distribution inside the subject in the same plane. The obtained results show
the strong nonuniformity of the field distribution produced by base-station antennas in urban environments and the importance of an accurate modeling of the real
environment in which the exposure takes place. As expected, the lowest field levels
are experienced by the subject standing in the street due to the high distance from
the antenna and to the angled position with respect to the antenna pointing direction. In order to better identify the power absorbed inside the main body organs, the
1 g avg SAR values are reported in Table 5.7.
8 m
Antenna
6 m
30 m
2 m
Antenna
6 m
20 m
10 m
Antenna
6 m
30 m
(a)
(b)
(c)
Figure 5.26 Exposure scenarios (a) subject on the building roof, (b) subject on the balcony,
and (c) subject on the street. (From Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi. 2000. IEEE
Trans Microw Theory Tech, 48, 11. With permission.)
180
[V/m]
[V/m]
5
[mW/kg]
160
1
140
10 −1
120
6
5
4
3
2
1
0
6
5
4
3
2
1
0
180
160
140
120
100
80
60
40
20
0
(cm)
0 20 40
10
−2
10
−3
100
80
60
10
−4
40
20
0
0 20 40

(cm)
(cm)

(a)
(b)
(c)
(cm)
Figure 5.27 (See color insert.) Subject on the building roof: (a) Erms when the subject is absent
(b) Erms when the subject is present (c) SAR distribution inside the subject. (From Bernardi, P.,
M. Cavagnaro, S. Pisa, and E. Piuzzi. 2000. IEEE Trans Microw Theory Tech, 48, 11. With permission.)