Low-power exclusion clause for wireless devices operating at close distances to the human body

Electrically small antennas confine their currents in a small environment, which gives rise to a high SAR in the close near field when comparing to larger antennas with widely spread currents. Based on simple geometrical assumptions on antenna size and current distribution, a low-power exclusion clause can be derived for the exposure of the human body in the near-field of portable transmitters. The approach is demonstrated for a large number of antennas at 900MHz and 1800MHz.