Directional handset antennas and human head at Ka-band: importance of skin layer

Non-directional handset antennas at microwave frequencies such as Ka-band (30 GHz) may result in very high unaveraged peak specific absorption rate (SAR) in the skin layer of the head. However, the peak SAR and the absorbed power can be significantly reduced by using directional antennas. Since most power absorption occurs in the thin skin layer at Ka-band frequencies, the consideration of the skin layer in EM modeling would be essential. In this paper, the SAR distributions and radiation patterns with non-directional and directional antennas are compared to emphasize the importance of the directional antennas at Ka-band.