Radio-wave exposure of the human head: analytical study based on a versatile eccentric spheres model including a brain core and a pair of eyeballs

Abstract

A versatile eccentric-spheres model of the human head is used in this paper to investigate radio-wave absorption. Numerical results, obtained by use of an exact analytical solution, are presented for the total, percentage, and gram-specific absorption. Interest is mainly in the brain and in the eyes of an adult or an infant head. Our model comprises a host sphere and several spherical inclusions, all concentrically stratified with respect to their own center. Any number of inclusions and any number of concentric layers for the host sphere and each one of the inclusions can be considered. Excitation is provided either by a plane-wave or by a nearby electric dipole. The analytical solution is obtained by use of the indirect-mode matching method. The theory of this paper and the accompanying computer code constitute a versatile tool for analytical studies of cellular-phone interactions with the human head. Specific absorption rate maps in a horizontal cross section of the head model manifest the existence of hot spots in the eyes and near the center of the brain.

Communication scheduling to minimize thermal effects of implanted biosensor networks in homogeneous tissue

“…Moneda et al [11] investigate radio frequency wave absorption on a human head model. Hirata et al [7] calculate the SAR for the interaction of the human eye with electromagnetic waves in the Industrial, Scientific, and Medical (ISM) frequency bands.…”

Time‐harmonic electromagnetic field analysis in multisphere model by Gumerov's method of two scalar potentials

“…Let the subscripts " [1]" and " [2]" denote the outer and inner spheres, respectively. With the wave vector (complex number) in this region denoted by k and the position vector with respect to the center of the sphere denoted by r, the scalar potential φ(r) representing the general solution to the scalar Helmholtz equation can be found as follows [3]:…”

“…However, such models are too simple in shape, and the verification is not sufficiently reliable. On the other hand, for models involving an arbitrary number of eccentric or separate nonoverlapping spheres, Moneda and colleagues [2] and Gumerov and Duraiswami [3] have shown that exact solutions for the time-harmonic electromagnetic field can be obtained by analytic methods using an infinite series expansion applied to the Helmholtz field. Using such calculation results for the aforesaid verification problem allows considerable improvement of reliability.…”

“…Moneda and colleagues reported analytic results for a 10-eccentric-sphere model of the human head [2]. Their analysis is based on the extended Mie theory using vector spherical wave functions, and a system of linear governing equations is obtained by matching of boundary conditions using the weighted residual method.…”

Sar and Temperature Elevation in a Multi-Layered Human Head Model Due to an Obliquely Incident Plane Wave

“…The values of ρ i for the different tissues of the model are taken from [10] and are given in Table 2.…”