Gaussian Beam Modeling of Sar Enhancement in Paraxial and Non-Paraxial Regions of Biological Tissues

Abstract

Abstract-A polarized 3D-electromagnetic wave propagating from an aperture source into a lossy medium can be modeled by an astigmatic Gaussian beam model (GBM) of complex source coefficients that characterize a radiating antenna uniquely. The source coefficients are determined numerically from phantom experiments, and then used in simulations of specific absorption rates (SAR), in both homogeneous and layered biological media, resulting in good agreement with experimental data. This paper shows that for an x-polarized E-field the GBM simulations of SAR enhancement or focus in the axial, z-directed, paraxial region are accurate, but approximate in the transverse, y-directed, non-paraxial regions due to a focal shift.

Complex Polar Coordinates in Electromagnetics

“…With regard to time-harmonic propagation problems, complex extensions of the coordinates have been used to study beam solutions, [3][4][5][6][7]. Other authors have studied the complex extension of coordinates in the Laplace equation solutions and the full wave equation solutions, [8].…”

3d Complex Beams in the Spatial and the Spectral Domains

“…Much attention has been paid to paraxial solutions as Gaussian beams and the expansion of arbitrary solutions in terms of the Gaussian beam summation technique [1][2][3]. In this paper, time-harmonic fields obtained as exact beam solutions to the wave equation will be discussed.…”

Gaussian Beam Scattering on Two-Dimensional Periodic Aperture Array

“…In them the homogeneous dielectric slabs, one-dimensional periodic structures, two-dimensional periodic arrays of magnetodielectric layers are considered. A result of these studies is the knowledge that the pattern configuration, amplitude and phase distributions of the transmitted and reflected fields of beam can be different from that ones of plane wave and some distinctive effects like lateral shift, focal shift, angular shift, beam splitting appear in the scattered field of the beam [13][14][15][16][17][18]. Therefore, it is necessary to take into consideration this circumstance in the designing quasi-optical devices and particularly in the phased antenna system in the form of two-dimensional apertures array [19].…”