Assessing Whole-Body Absorption Cross Section For Diffuse Exposure From Reverberation Chamber Measurements

An original experimental protocol is developed to assess the whole-body absorption cross section of objects with arbitrary shapes and materials in diffuse fields at any operating frequency. This approach is important for dosimetry specifically in realistic environments wherein diffuse fields can be prominent. For this application, the knowledge of the whole-body specific absorption rate is critical and can be determined from the human wholebody absorption cross section. The whole-body absorption cross section is obtained from measurements performed in a stirred-mode reverberating chamber processed with the high-resolution parameter estimator RiMAX. To validate the proposed approach and highlight its robustness, the whole-body absorption cross section of a cylindrical phantom is experimentally and numerically determined at 1800 MHz. For both methods, the whole-body absorption cross section is shown to be independent on the orientation of the transceivers, indicating that it is indeed caused by diffuse fields. A good agreement is obtained between experimental and numerical finite-difference time-domain results with a relative deviation of about 17%. From the validation of this approach, the measurement protocol is applied to a real human at 1800 MHz resulting in a whole-body absorption cross section of 0.95 m², 1.01 m², and 1.11 m² for a sitting, standing, and standing with stretched arms posture, respectively.