| Summary: | This thesis is a research conducted to find out if the specific absorption rate (SAR), imposed on the human head from cellular phones, can be reduced without having an significant impact on the overall performance and reception of the phone. The SAR values are influenced by various different variables like, type and size of the antenna, position of the antenna relative to human head, radiated power from the antenna, distance and angle from human head and finally the material covering the phone. The methodologies that will be used are to investigate three different approaches to SAR reduction. First approach is to investigate if the size and type of the material shielding the human head have significant impact on the SAR radiation, second approach is to investigate if the angle of the phone in relation to human head have significant impact and as the third approach is to investigate if it is possible to change the composition of the material which would ultimately lead to SAR reduction. Electric properties of the material are described by two variables conductivity and permittivity, and in the third part of the thesis I will change these two variables and then investigate how the SAR values change. Result will be presented as a 3D graph and it will directly present how SAR values relate to the material used as a phone casing. The distance and antenna variations will not be investigated. The distance values will be fixed to 2.5 cm from the human head and the antenna length will be quarter of the 900 MHz wave length. The investigations will be performed in a simulation program called FEMLAB and the results will be showed in text and figures.
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