Specific Absorption Rate Distributions in a Heterogeneous Model of the Human Body at Radiofrequencies

摘要

The electric field distribution of the rate of energy absorption referred to as the specific absorption rate (SAR) in a biological body is a complex function of several exposure parameters such as frequency, intensity of the incident field, polarization, source to object configuration (near-field vs. far-field) and the body characteristics such as size, shape, and dielectric properties. An experimental approach was employed to determine SAR patterns in a full scale heterogeneous model of man exposed to radiofrequency fields at 160, 350, and 914 MHz in the far and near fields for two polarizations. The model had an anatomically correct shape and contained a skull, spinal cord, rib cage, and all major bones (except those in the feet and hands), brains, lungs, and muscle tissue. The square of the electric field inside the model was measured by a small diameter electric field probe. Data acquisition, exposure conditions, and data processing were under computer control. Specific circuitry including an optical link was used to interface the electric field probe with the computer. Extensive data were obtained, analyzed, and compared with the data for a homogeneous model.