Theoretical Approach of the Interaction Between a Human Head Model and a Mobile Handset Helical Antenna Using Numerical Methods

Abstract

Abstract-The interaction of a helical antenna, mounted on a mobile handset, with a human head phantom is investigated in this paper. Using the Genetic Algorithms (GA) technique combined with the Method of Moments (MoM), an optimization of the antenna structure is achieved regarding the input impedance at the operating frequency. The Finite Difference Time Domain (FDTD) method is then applied to simulate the handset's function in the close region of a spherical homogeneous and heterogeneous head phantom. A formula, based on an application of an existing model proposed by Kuster and Balzano for dipole antennas, provides a rather accurate prediction of the induced Specific Absorption Rate (SAR) values in the human head due to the radiating helical antenna. The concept of relating the SAR to the current on the antenna is used in this study to formulate the final expression. Moreover, using the theory of regression, the results of the calculated peak or average SAR are correlated with the distance between the antenna and phantom and with the standing wave ratio (SWR) at the antenna feed point. Thus, the conception that the SAR is indeed related to the antenna operational parameters is reinforced by the outcome of the current study.

Modelling the Interaction between the Antenna and the Human Head by the Technique of Artificial Neural Network

“…According to the working frequency, the antenna power, the power radiated by the antenna, the dielectric properties of tissues, the distance between the antenna and the head gives a look of reflection coefficient, a SAR value (between 10 and 1 g), the value of radiation efficiency, the value of the input power, the input impedance. So from this explanation, we have took as input the reflection coefficient of the antenna, the working frequency, the distance d between the antenna and the body, the input power, the output power, the permittivity of fabric, the fabric density and the conductivity of tissue and as an output they obtained the reflection coefficient, the SAR values averaged over 10 and 1 g (Hombach et al, 1996;Okoniewski and Stuchly, 1996;Kouveliotis and Panagiotou, 2006;Sager et al, 2003), the radiation efficiency, the power absorbed and the input impedance. Figure 3 shows the Neural model applied to the interaction.…”

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].…”

“…Various studies on this subject exist [8][9][10][11][12][13][14][15][16][17][18][19][20], most of which mainly delve into the consequences of mobile-phone usage. Yet, devices and communication terminals operating in other frequency bands have also gained substantial interest in the last 15 years.…”

“…The most used method to solve the electromagnetic problem dealt with this area is the finite-difference time-domain (FDTD) technique [10][11][12][13]. Although, in principle, the solution for general geometries does not require any additional effort with respect to the standard method, the technique requires the definition of the discretized space by assigning to each cell its own electromagnetic properties, which is not an easy process [12][13][14][15].…”

VHF-Lb Vest Antenna

“…In order to verify that the antenna is not hazardous for human body we investigated the effects of antenna radiation on a human body Our studies concentrate on the evaluation of SAR [15][16][17][18][19][20][21][22]. Although the interaction between electromagnetic fields (EMF) and a human body has been of interest to the scientific community [23,24], the main concern was the effects of antennas on human head for cellular phone frequencies [25][26][27][28][29]. Thus to specify the acceptable levels of EMF absorption on human body some regulated standards were reviewed [30][31][32] and compared with simulations and measurements.…”