Dependence on antenna output power of temperature rise in human head for portable telephones

Since biological hazards due to RF exposure are caused mainly by a temperature rise in tissue, the localized specific absorption rate (SAR) should be related to the temperature rise in the human head for portable telephones. Although the SAR is known to be directly proportional to the antenna output power of portable telephones, the dependence of temperature rise on the antenna output power remains unclear. In this paper, the relationship between the peak temperature rise in a human head and the antenna output power is investigated by using the finite-difference time-domain (FDTD) method. It is found that the peak temperature rise is approximately proportional to the antenna output power below 1 W and also that the peak temperature rise in the brain can be estimated from its blood-flow and heating potential.