Temperature Rise Induced by Wire and Planar Antennas in a High-Resolution Human Head Model

The peak temperature rise in a high-resolution heterogeneous head model due to the electromagnetic energy absorption from wire and planar antennas are investigated within the frequency range of 900-6000 MHz. Electrically small nonresonant antennas, resonant antennas, and planar directive antennas are considered both radiating toward the direction of the head as well as away from the head. It is observed that the maximum temperature rise due to dipole antennas are between 0.17 and 4.07°C for 1 W of input power for antenna to head separation distances between 5 and 20 mm. Planar antennas, e.g., planar inverted-F antennas and microstrip patches induce a peak temperature rise of 0.04-2.28°C for 1 W depending on their orientations and distances from the head. Based on the directly simulated maximum temperature rise data an empirical formula is developed, which estimates the maximum temperature rise in the head as functions of antenna to head separation distance, operating frequency, and antenna free-space bandwidth.