Analysis of the Interaction Between a Layered Spherical Human Head Model and an Arbitrary Shaped Antenna Using a Hybrid Green/MoM Technique S. Koulouridis, K.S. Nikita The interaction between an arbitrarily shaped wire antenna and a three-layer lossy dielectric sphere, representing a simplified model of the human head, is analyzed theoretically. The proposed technique is based on the theory of Green’s functions in conjunction with the Method of Moments (Green/MoM). The Green’s function of the three-layer sphere can be calculated as the response of this object to an elementary dipole of unit dipole moment. The antenna is simulated with the aid of Method of Moments. Appropriate boundary conditions are imposed on the surface of the antenna leading to a linear set of equations. The solution of the linear system determines the unknown coefficients arising from the MoM technique. Then the electric field at any point in space, including the interior of the sphere, as well as other parameters of interest (i.e., the current distribution, the input impedance, the radiation pattern of the antenna) can be calculated. The main purpose of this analysis is to provide a reliable tool for the solution of specific canonical problems referring to the dosimetric evaluation of potential health hazards in mobile telecommunications. The semi-analytical character of the proposed method permits the benchmarking of purely numerical techniques applied to more realistic head geometries. Finally the developed method can be used to evaluate different antenna designs. I. INTRODUCTION The wide use of hand-held transceivers during the past years has led to the increasing public concern about potential health hazards and compliance with safety standards. Therefore, an increasing demand for accurate dosimetric calculations inside lossy dielectric bodies exposed to the near field of electromagnetic devices has been imposed. The absorbed power in the human head is one of the most crucial parameters to be defined. On the other hand the effect of human head on the performance of the mobile phone antenna and the need for improvement of antenna designs have further motivated the efforts for studying the interaction between mobile phones and human head. Several calculation methods, such as Finite Difference Time Domain (FDTD) algorithms [1], Method of Moments (MoM) [2], Multiple Multipole Method (MMP) [3] and analytical or semi-analytical methods [4]-[7], have been developed by many researchers to deal with this complex electromagnetic interaction problem. The use of FDTD has dominated over the other numerical methods. In the last few years, an ever-increasing effort has been made to develop antennas of smaller dimensions without significant reduction of performance, such as helical antennas. Recently, several formulations of FDTD or its combination with the MoM have been proposed to study the interaction between helical antennas and human head [9]-[10]. However, although numerical methods, such as the FDTD, are able to model anatomically detailed human head structures, difficulties are encountered in modelling antenna structures not conforming to the used grid, while also significant discrepancies can be observed in the results obtained by different groups nominally using the same numerical method, even for well defined canonical cases [8].