Natural coupling distance for human exposure to electromagnetic fields

The rationale for deriving basic restrictions to electromagnetic field (EMF) exposure and their associated safety margins is not fully standardized and diverse values are employed depending upon the thermal effect being considered. With the recent capabilities of modern computers, hybrid Maxwell´s and heat-transfer equations have been solved for the human exposure to EMF problem. In this contribution, a human head is exposed to 4 W of power at 5725 MHz (corresponding to the maximum EIRP for WiMAX Band C). Peak SAR values along a coronal plane containing the hypothalamic region, and its effects on temperature increase, have been observed. A natural coupling distance between the antenna and the human head, and the skull being a protection for thermal stress due to EMF exposure have been confirmed, validating previous studies suggesting that a combined EM-thermal basic restriction would represent more accurate safety limits, reducing the uncertainties for deriving the reference levels.