Computation of SAR Distribution in a Human Exposed to Mobile Phone Electromagnetic Fields

The most important dosimetric parameter used to assess human exposure to RF electromagnetic flelds is SAR. Since SAR depends from dielectric properties of biological tissues and induced electric fleld, dielectric properties of human body tissues are addressed. At mobile communication frequencies biological tissues may be considered as lossy dielectrics. Radiation from mobile phone on talk position mostly covers human head. In order to assess human exposure to mobile phone electromagnetic flelds we have run simulations with SEMCAD (FDTD code) for model: human head + mobile phone. Obtained result of Spatial Peak SAR averaged over 1g of biological body tissues is 2.1mW/g for typical transmitting power of mobile phone 250mW, while obtained result for Spatial Peak SAR averaged over 10g of biological body tissue is 1.35mW/g. Visually SAR distribution is presented. As noticed Peak SAR appears near human ear. Even though mobile phone is considered by many as fundamental of their lifestyle, exposure to cellu- lar mobile communication electromagnetic flelds has raised individual and public concern regarding possible adverse efiects to people exposed to such radiation. In developed countries more than half of population owns and uses on daily basis a mobile phone. Moreover increased usage among all age groups including children and elders is being reported. Exposure of humans to electromagnetic fleld of mobile phone is being followed by many govern- ments, research projects, industries and general population that are concerned regarding potential biological and health efiects caused by mobile phone radiation. At frequencies above 100MHz, including here frequencies of mobile telephony the most impor- tant dosimetric parameter used to assess human exposure to electromagnetic flelds is SAR (Speciflc Absorption Rate). Dosimetric studies are performed to quantify the interactions of electromagnetic flelds with biological tissues. Whether they are numerical or experimental the SAR distribution has to be determined. For this reason almost all national and international safety guidelines and recommended limits on human exposure to electromagnetic flelds are given in terms of SAR. Radiation from mobile phone in talk position covers mostly human head. Determination of induced electrical fleld inside a human head exposed to mobile phone radiation is a complicated issue having in mind a near distance between phone and human head, dielectrical properties of head biological tissues etc. Due to sensitivity and ethics on experiments with humans in order to calculate SAR in human head difierent numerical methods may be used. Finite Time Difierence Domain is shown as very appropriate (1) thus software SEMCAD Jungfrau that is based on this method is used for simulations and SAR calculation in this paper. The SAR, time rate of RF energy absorbed per unit mass of body biological tissue is given as: SAR = (ae + ! "0 " 00 ) E 2 ‰