Effect of Shape, Size and Electrical Properties on Specific Absorption Rate (SAR)

This paper presents the dependency of SAR distribution in the human brain and eye on the shape, size, and electrical properties for different frequencies. Calculations were carried out using the Finite Difference Time Domain (FDTD) Method. The results indicate that the SAR distribution does not much depend on the shape and size but it depends mainly on the electrical properties of the tissues. There is a drop in the magnitude of the SAR in the brain when moving from a cubical model to the spherical model. There is a magnitude drop in the eye, when going from a spherical model to the cubical model. For both brain and eye, when the size is decreased, the volume is reduced and therefore the electromagnetic energy absorption goes up. The human eye at 2500 MHz was considered to observe how the electrical properties of the tissues affect the electromagnetic energy absorption in an organ. When relative permittivity is perturbed in small percentages with conductivity remaining unchanged; the value of the maximum SAR also changes by small values. However, both these cases, when the electrical properties are changed, the location of maximum SAR remains unchanged. It is exactly at the center of the eye.