TaBlE 1.8 Permittivity Parameters for the Debye Equation and Dimensions of
Skin Models Used in Calculations
Forearm Model
Palm Model
Parameter
1
2
3
2
3
SC
ε ∞
–
2.96
2.96
3.63
3.63
Δε
–
–
–
9.7
9.5
d (mm)
–
0.015
0.015
0.43
0.42
σ (S/m)
–
0
0
0
0
E − + D
ε ∞
4.0
4.0
4.0
4.52
4.52
Δε
32.0
32.6
32.4
27.2
26.4
d (mm)
∞
∞
1.45
∞
1.85
σ (S/m)
1.4
1.4
1.4
1.4
1.4
τ × 10 12 (S)
6.9
6.9
6.9
6.9
6.9
Source: Alekseev, S. I., O. C. Gordiienko, and M. C. Ziskin. 2008. Reflection and penetration depth of millimeter waves in murine skin. Bioelectromagnetics 29:340–4.
Note: SC stands for stratum corneum, E + D stands for the rest of the epidermis plus the
dermis, and d stands for layer thickness. Model 1—homogeneous skin with E + D; model 2—
SC and E + D; model 3—SC, E + D, and fat.
61
Coupling of Electromagnetic Fields into Biological Systems
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Frequency (GHz)
Reflection
Palm
Forearm
30
40
50
60
70
80
FigurE 1.35 Measured power reflection coefficient in the forearm and palm as a function of
millimeter-wave frequency: Solid lines are for three-layered skin model containing the stratum
corneum and epidermis plus dermis. Error bars represent SD; n = 12. (From Alekseev, S. I., and
M. C. Ziskin. 2007. Human skin permittivity determined by millimeter wave reflection measurements. Bioelectromagnetics 28:331–9. With permission.)
penetration depth δ (distance to e −1 of surface values of the mmW field), and SAR in
human skin calculated for homogeneous and multilayer planar models are shown in
Figures 1.36 through 1.38.
The transmitted power density profiles at 42 and 61 GHz in skin model 3 (Table 1.8;
SC, E + D, and fat) are illustrated in Figure 1.36. It can be seen that exposure at 61 GHz
produces a higher power density in the epidermis, whereas exposure at the lower 42 GHz
is more intense in the dermis. The frequency dependence of power deposition is further
illustrated by differences in the penetration depths calculated for the forearm and palm