Local Specific Absorption Rate (SAR) Measurement System for Human Body in Realistic In-Vehicle Scenarios

Specific absorption rate (SAR) measurements for the human exposure in vehicles generally follow the standards such as IEC 62209 series, but these standards do not account for the in-vehicle propagation environment, including reflections, multipath effects, and cavity resonances. In recent years, an increasing number of studies have focused on evaluating SAR in realistic scenarios. Numerical simulations have indicated that enclosed vehicle cabins significantly affect the SAR distribution. However, systematic measurement results and analyses of in-vehicle SAR have not been sufficiently reported. To address this gap, this paper proposes an in-vehicle SAR measurement system capable of estimating the local SAR on a full-body phantom under realistic vehicular conditions. Compared with conventional planar phantoms, a seated human phantom is designed to better represent in-vehicle postures. Tissue-equivalent liquids covering 0.2-6 GHz are developed to satisfy the requirements of IEC 62209-3. An E-field monitoring module interfaces with the phantom to enable local SAR measurements at different depths within the liquid. A three-antenna method is used to calibrate the E-field probe in the liquid. Simulation and measurement results demonstrate consistent local SAR evaluations with good agreement. Furthermore, the in-vehicle local SAR is measured and compared with existing numerical in-vehicle local SAR assessments. The proposed measurement system provides a practical and convenient approach for in-vehicle local SAR estimations.