Fast and efficient FDTD simulations of personal wireless devices for SAR compliance testing and antenna design

We have used an efficient implementation of the PML boundary according to the formulation proposed by Sullivan (1977) to truncate the human head model for cellular telephone simulations. Different from the truncation method previously presented by the authors, the new method does not require any symmetry considerations. Because of the basic observation that a large percentage of the power absorbed in the human head model is concentrated in the proximal ear and a limited volume of the head behind it, it was possible to gradually truncate the head model in the ear-to-ear (x) direction, back-to-front (y) direction, and bottom-to-top (z) directions. It was found that it is possible to retain just 4% of the original volume of the head model to obtain 1- and 10-g SARs within 1% accuracy at the frequency of 1900 kHz. At the frequency of 835 MHz, since the actual shape of the head in proximity of the ear region affects the radiation from the cellular telephone and its radiated power, it was necessary to retain approximately 15% of the head model to achieve 1% accuracy for the 1- and 10-g SARs. The method allowed us to complete cellular telephone simulations in less than 5 minutes at the frequency of 1900 MHz using a commonly available PC. The method can be efficiently used for SAR compliance testing of wireless devices and may also be used as an efficient tool for the design of handset antennas.