How to Calculate Specific Absorption Rate for Cell Phones

How to Calculate SAR - Definition, Formula, Chart

Definition:

SAR is amount of radiation which is absorbed by the human tissues while using the cell phones. When the SAR rate is very high it represents the radiation absorbed is also very high. This SAR value is usually measured in units of watts per kilogram (W/kg) in either 1 or 10 gram of tissue.

Formula:

SAR = (σ × Erms2) / ρ Where,

SAR = Specific Absorption Rate σ = Conductivity of various human tissues Erms = RMS of electric intensity of the body ρ = Density of human tissue

Chart 1:

Learn the Electrical properties of different tissues in the body from the following chart.

Electrical properties of different tissues at 900 MHz
Tissue Erms (V/m) σ (S/m) ρ (kg/m3)
Skin 39.5 0.69 1010
Bone 17.4 0.19 1810
Brain 45.8 0.76 1025
Chart 2:

Learn the SAR value in the human head for different distance between human and antenna from the following chart.

Calculated SAR value in the human head for different values of D
Distance between
antenna and human head (D)
10 mm 15 mm 20 mm 25 mm 30 mm
SAR value (W/kg) 9.9629 9.3130 9.0162 8.7906 8.1281

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