Parametric Study of Power Absorption Patterns Induced in Adult and Child Head Models by Small Helical Antennas

Abstract

Abstract-A comparative assessment of power absorption in adult and child heads exposed to a small helical antenna at 1710 MHz, is presented, emphasizing the effect of age related parameters. Finite Difference Time Domain simulations are employed to study the interaction between MRI-based head models and a mobile communication terminal equipped with a small helical monopole. A semi-analytical method, based on Green's function theory and the Method of Moments, is used to study the absorption in threelayer spherical head models exposed to a small helical dipole. SAR patterns in child head models derived by non-uniform scaling of adult ones were assessed against SAR patterns computed in child heads derived by uniform downscaling procedures. In both realistic and canonical exposure scenarios, comparable levels of absorbed power Corresponding author: K. S. Nikita (knikita@cc.ece.ntua.gr). 50Christopoulou, Koulouridis, and Nikita (maximum difference: 12%) in adult and child head models were observed. Dependence of SAR values upon separation distance and tissue dielectric properties was quantitatively assessed. In realistic exposure scenarios, the reduction in peak SAR values was 60-80% for a 1 cm increase in distance and up to 16% for a 110% to 90% decrease in dielectric properties values with reference to the nominal value of 100%. These trends were respectively less (55-65%) and more (up to 24%) emphasized in the corresponding canonical exposure scenarios.

A Novel Dielectric Conformal FDTD Method for Computing Sar Distribution of the Human Body in a Metallic Cabin Illuminated by an Intentional Electromagnetic Pulse (Iemp)

“…On the other hand, we know that some very effective threedimensional (3-D) FDTD algorithms have been reported recently for predicting biological effects due to electromagnetic exposure, in particular for SAR computation of the human head or body in the presence of a non-intentional electromagnetic radiation [5][6][7][8][9][10][11][12][13][14][15][16][17]. However, it must be understood that, in order to obtain an accurate SAR solution for the human head or body using the FDTD method, the spatial mesh size should be small enough so as to effectively suppress its staircase errors.…”

Design Analysis of Ferrite Sheet Attachment for Sar Reduction in Human Head

“…So there is a need to reduce an effort for reducing the spatial peak SAR in the design stage of phone model because the possibility of a spatial peak SAR exceeding the recommended exposure limit cannot be completely ruled out [2,3]. The interaction of the cellular handset with the human head has been investigated by many published papers with considering; first, the effect of the human head on the handset antenna performance, including the feed-point impedance, gain, and efficiency [4][5][6][7][8], second, the impact of the antenna EM radiation on the user's head due to the absorbed power, which is measured by predicting the induced SAR in the head tissue [7][8][9][10][11][12].…”

Analysis of Materials Effects on Radio Frequency Electromagnetic Fields in Human Head

“…Recent studies show that the presence of a hand also changes the radiation performance of a mobile phone and, hence, changes the SAR in the human head [22][23][24][25][26][27][28][29][30][31][32][33]. In [34], the SAR values for two different human body postures were calculated and resulted in increasing values of the average peak SAR.…”