Computed SAR distributions for the occupants of a car with a 400 MHz transmitter on the rear seat

Numerical simulations have been used to investigate the impact of occupant distribution on the field exposure threat due to a transmitter operating at 400 MHz inside a car. Eight different occupancy configurations involving the driver and up to three passengers were considered, and both 10 g and 1 g SAR measures were determined. The models suggest that mean SAR limits are likely to be reached at lower power levels than would be needed to reach maximum SAR limits. The presence of the vehicle structures is found to result in higher mean SAR values for all occupant locations, although maximum SAR levels are lower with the vehicle for the driver position. It is concluded that evaluating the in-vehicle field exposure threat by comparing average fields over the interior of the empty vehicle with the reference levels recommended for assessing the exposure of the general public provides a safety factor approaching two for the source configuration under investigation.