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Computation Of SAR Distributions On the Human Head
due to Personal Wireless Devices Using 3D FDTD Technique
Neelakantam Venkatarayalu. Advisor : Prof. Annapurna Das Abstract The 3d Finite Difference Time Domain (FDTD) numerical electromagnetic technique has been studied and applied to study the effects of electromagnetic radiations from Cellular mobile phones on the Human head. To ensure the validity of the technique, it was first applied to a rectangular waveguide problem and the simulation results were compared with the theoretical results. Mur's 2nd order absorbing boundary conditions(ABC) were applied for the problem involving the head model. To study the effect of Mur's ABC, it was applied to the case of an isotropic radiator inside the computation domain. Once the validity of the technique and the ABC used was ensured, a human head model was generated, which was to be incorporated in the FDTD computational domain. The model is based on Magnetic resonance images (MRI) and the entire head was spatially discretized into cells of dimension 0.5 cms. The generated model was tilted by an angle of 10° and 20° to the vertical. A lambda/2 dipole of equivalent length 10.5 cms was used as the source of 600mW of electromagnetic power, the same power radiated from a cellular mobile phone operating at 835MHz. The specific absorption rate (SAR) was calculated for the three head models with the source at distances of 1cm and 2cms from the head. The computed peak SAR was around 1.35 W/Kg when the radiator was 1cm away from the head, which is below the IEEE/ANSI standards upper limit of 1.6W/Kg. It was observed that the SAR reduces significantly with increase in the distance between the head and the source. The simulation results lead to the conclusion that the SAR generated in the tilted head models were less than that of the vertical head model, all being below the IEEE/ANSI exposure limit of 1.6 W/Kg. Back |