Effect of High Frequency Electromagnetic Fields on Homogenous and Inhomogeneous Human Head Models Ossama E. Gouda 1 , Adel Zein E. M. 2 , and Ghada Amer 3 1 Faculty of Engineering, Cairo University, Giza Egypt 2 Higher Institute of Energy, South Valley University, Aswan, Egypt 3 Higher Institute of Technology, Benha University, Benha, Egypt Abstract—This paper describes the research work done by using the method of moment in investigating the effects of high frequency electromagnetic field (EM) on a homogeneous and inhomogeneous human head at various frequencies. The behavior of the human head under EM radiation is modeled as a homogenous model and a multilayer model in order to assess biological effects on the human head. The specific absorption rate (SAR) in the human head model is calculated, where the SAR is the main parameter used for indicating the effects of EM field. Index Terms—EMF, SAR, Human head, Method of moments. 1- INTRODUCTION HE increasing use of electromagnetic (EM) devices in our society for a variety of purposes has caused growing concern about possible health hazards produced by EM radiation. This concern has led to an increased intensity of research aimed at identifying possible hazards due to EM radiation. In particular, a considerable amount of theoretical work has been devoted to the investigation of EM effects on human being using various shapes [1]. In this paper, two models of the human head are used; the first is a homogeneous model and the second is inhomogeneous model and classified into only three layers of material (average skin dray/wet properties for first layer, average skull properties for second layer and average brain properties for third layer). The tissue parameters are derived by Gabriel, et al. [2]. This data is available on Federal Communication Commission's website in the United States. Table (1) shows the real part of the dielectric permittivity (εr), conductivity (σ S/m) and mass density (ρ kg/m3) of tissues used in the simulation of three layer model and homogenous model at high frequency electromagnetic field (900MHz and 1800MHz) [2]. The applied antenna is consisted of a quarter-wavelength monopole (of radius 0.0025m at 900MHz and 0.0012m at 1800MHz) mounted on a mobile handset (treated as a metal box of 5cm*8cm*18cm), and radiated power of 0.32 watt. The purpose of this paper is for the investigation of interactions between the handset antenna and the human head. Where the SAR is the main parameter used for indicating the effects, one gram average SAR on the above systems is calculated, which is recommended its limit value 2W/kg in the Federal Communications Commission, FCC and International Commission on Non- Ionizing Radiation protection, ICNIRP. In addition to these results, ten grams average SAR is calculated [3]. Also the results of the three layer model are compared with those of homogenous model at 900MHz [4]. 2-FEKO SIMULATION AND VALIDATION The FEKO program is based on the Method of Moments. Electromagnetic fields are obtained by first calculating the electric surface currents on conducting surfaces and equivalent electric and magnetic surface currents on the surface of a dielectric solid. The currents are calculated using a linear combination of basis functions, where the coefficients are obtained by solving a system of linear equations. Once the current distribution is known, further parameters can be obtained e.g. the near field, the far field, radar cross sections, directivity or the input impedance of antennas [5]. The simulation procedure is as follows: 1-Create the human geometry model 2-Define the frequency, human parameters and meshing parameters, 3-Create the monopole and mobile handset, define parameters for segmentation, excitation and radiation power 4-Solving the problem 5-Calculate the near field and SAR. Table (2) shows the calculation information from FEKO program. 3- RESULTS AND DISCUSSION A. Calculation Position As it cannot be expected that the user will hold the mobile phone exactly in one well defined position, therefore there are different operational conditions. Let a reference line describing the phone is defined as a line which connects the center of the ear piece with the center of the bottom of the case and the human head position is given by means of a reference plane defined by the following three points: auditory canal opening of both ears and the center of the closed mouth [6]. With these definitions the calculation position is given by: The telephone line shall lie in the reference plane (40 degrees around x-axis). The angle between the phone line and the line connecting both auditory canal openings shall be reduced (10 degrees around y-axis) until the device touch the human head. A FEKO simulation of the human head and the handset antenna interaction is shown in figures (1-a) and (1-b). B. Specific Absorption Rate It is generally accepted that the Specific Absorption Rate T 978-1-4244-4346-8/09/$25.00 ©2009 IEEE 2009 6th International Multi-Conference on Systems, Signals and Devices