Specific absorption rate perturbations in the eyes and head by metallic spectacles at personal radio communication frequencies

• Main Author: Whittow, William
• Published: University of Sheffield 2004
• Subjects: 612.01427
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412247

The research in this thesis involves the absorption in the human head of microwaves in the frequency range 0.5 to 3GHz with the excitation positioned in front of the face. It is hypothesised that metallic spectacles can significantly affect the absorption in the head. The effects of metallic spectacles have been primarily investigated using computer modelling. The finite-difference time-domain (FDTD) is the most common computational tool used in bioelectromagnetics. For this research an independent, specially written FDTD code has been used. The accuracy of the code was carefully validated against controls. Two anatomically accurate heads were implemented into the FDTD code. Different shapes and sizes of metallic spectacles were modelled. The materials that the spectacles were made of were also investigated. Realistic and geometric spectacles were considered. Vertically and horizontally polarised plane waves as well as vertically and horizontally orientated dipoles are used as sources. A genetic algorithm (GA) was employed as a search technique to optimise the spectacles for the specific absorption rates (SAR) in the eyes and the head. Measurements were also made of a phantom with metallic spectacles. Results showed good agreement with the FDTD code. Results confirmed the hypothesis that metallic spectacles can significantly affect the SAR in the head and particularly in the eyes.