TaBlE 1.5 SAR Data for a Monopole (Covered by a Rubber Slab) over a Metallic PCB
Covered by a Plastic Box
Cheek Position
Tilted Position

Frequency
SAR 1 g (W/kg)
SAR 10 g (W/kg)
SAR 1 g (W/kg)
SAR 10 g (W/kg)
835 MHz
7.5
5.2
5.0
3.4
1900 MHz
9.2
5.3
13.1
7.3
Source: Kainz, W., A. Christ, T. Kellom, S. Seidman, N. Nikoloski, B. Beard, and N. Kuster. 2005. Phys
Med Biol 50:3423–45. With permission.
31
Coupling of Electromagnetic Fields into Biological Systems
TaBlE 1.4 Comparison between CAD-Derived Phone Models and Their Equivalent PlasticCovered Metal-Box Models
Power Absorbed
Power Absorbed in
in the Head
the Hand
SAR 1 g
(Percentage)
(Percentage)
835 MHz phone
CAD model
2.17
23.8
17.2
(radiated power:
600 mW)
Plastic-covered
metal-box model
2.39
26.7
17.8
1900 MHz phone
CAD model
0.78
32.1
17.9
(radiated power:
125 mW)
Plastic-covered
metal-box model
0.64
31.4
18.1
Source: Gandhi, O. P., G. Lazzi, A. Tinniswood, and Q. S. Yu. 1999. Bioelectromagnetics 20 (Suppl 4):
S93–S101.
Common or intended headphone positions have been used to compute SAR distributions in the head. For example, the SARs computed for 1 and 10 g of tissue at 835 MHz and
1900 MHz, for 1.0 W of radiated power, are presented in Table 1.5. The computation was
done using the cell phone model of a generic monopole, which was covered by a rubber
slab (71 mm long for 835 MHz and 36 mm long for 1900 MHz) and placed on a flat metallic plate (40 × 1 × 100 mm), representing the PCB, inside a plastic box (42 × 21 × 102 mm).
Apart from the typical observation of higher SARs (approximately double) for the higher
operating frequency and the conservative estimation of 10-g averaged SAR values, it is
observed in a comparison between “cheek” or “tilt” headphone positions that the cheek
position always gives the higher maximum SAR.
A representative list of computed SAR values for cellular telephones operating at 900
and 1800 MHz is given in Table 1.6. For the two types of simulated antenna configurations, the results do not exhibit any consistent effect of antenna model on induced SAR.
However, the peak SAR tends to be lower for longer antennas compared with shorter
antennas at the higher frequency. It is interesting to note that some computed data based
on head and neck anatomy have recorded values for 1-g SARs that are twice as high as
those computed for 10-g SARs (Gandhi et al. 1999; Kainz et al. 2005).
It is significant from the energy coupling perspective that 40%–50% of the radiated
RF power is absorbed by the human body (Table 1.6); this was reported earlier by
other investigators also (Tinniswood, Furse, and Gandhi 1998; Gandhi et al. 1999).