Modelling the SAR and thermoregulatory response during far-field RF exposure

In this paper, the Pennes bioheat equation with a thermoregulatory model is used for numerical modelling of local peak temperatures as well as the body core temperature elevation in a realistic human body model for plane-wave exposures at frequencies 39, 800 and 2400 MHz. The electromagnetic power absorption is solved numerically using the FDTD method and the resulting temperature rise is solved from the bioheat equation for various different combinations of modelling parameters, such as the skin blood flow rate, models for vasodilation and sweating, and clothing and air movement. The results show that ignoring the thermoregulation and the blood temperature increase is a good approximation when the local 10-g averaged specific absorption rate is smaller than 10 W kg^-1. The most dominant thermophysiological factors affecting the peak temperature rises are related to the modelling of the tissue blood flow and its temperature dependence, while the body-core temperature rise is dominantly affected by the modelling of the sweating response.