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

Abstract

Abstract-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 whole-body 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 (FDTD) 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 m 2 , 1.01 m 2 and 1.11 m 2 for a sitting, standing, and standing with stretched arms posture, respectively.

On‐body calibration and measurements using personal radiofrequency exposimeters in indoor diffuse and specular environments

“…Figure b shows an illustration of the setup for measurements in the RC. The working area of the chamber where fields have uniform distribution [Bamba et al, ] is indicated with dashed lines. Room dimensions are 5.7 × 4.1 × 2.8 m 3 (length × width × height) which provides a volume equal to 65 m 3 .…”

Measurement of absorption cross section of a lossy object in reverberation chamber without the need for calibration

“…The measurement of the ACS of a lossy object is required for many applications, including the characterization of lossy objects on electromagnetic wave propagation used for communications in multipath environments such as interiors of mass transit vehicles or aircraft loaded with cargoes or passengers [9], biometrics electromagnetic exposure studies such as human's specific absorption rate [12], [13].…”

Inverse fourier transform technique of measuring averaged absorption cross section in the reverberation chamber and Monte Carlo study of its uncertainty

“…The averaged ACS can be measured in two ways. Firstly, it can be done by measuring the average net power transfer function G chamber [1], [11], [12], [13], or it can be determined by measuring the change of the reverberation chamber time constant τ [14].…”