A brain-equivalent solid phantom and its application to SAR estimation by the thermographic method

Recently, with the rapid proliferation of mobile communication devices, the effects of electromagnetic waves on the human body have drawn attention. A lthough these effects depend significantly on frequency, the thermal effect s due to absorption of the electromagnetic energy are considered predominan t at microwave frequencies. In general, as the guideline for the thermal ef fects, the power per unit mass absorbed in the biological body, namely, the specific absorption rate (SAR [W/kg]), is used. Cellular phones are employ ed in close proximity to the head where vital functions of the body are con centrated. Even if the output is weak, there is the possibility that the po wer absorption may become locally excessive. Therefore, it is extremely imp ortant from a safety point of view to establish an experimental evaluation procedure regarding the SAR for the human head. In this paper, the characte ristics of thermography are recognized by means of which the surface SAR ca n be measured, and thus the SAR distribution in an arbitrarily shaped mediu m. Using the biologically equivalent phantom developed in the authors' labo ratory for improving the conventional phantom used for the same purpose, a fundamental investigation is carried out as to how accurately the SAR distr ibution can be measured. (C) 2000 Scripta Technica.