A Novel SAR-Probe Calibration Method Using a Waveguide Aperture in Tissue-Equivalent Liquid

Nozomu ISHII  Lira HAMADA  Soichi WATANABE  

IEICE TRANSACTIONS on Communications   Vol.E97-B   No.10   pp.2035-2041
Publication Date: 2014/10/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E97.B.2035
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Measurement and Design Techniques on Antennas, Propagation and Wireless Systems)
specific absorption rate (SAR),  probe calibration,  tissue-equivalent liquid,  waveguide aperture,  

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A novel method for calibrating the probes used in standard measurement systems to evaluate SAR (specific absorption rate) of the radio equipment operating at frequencies over 3GHz is proposed. As for the proposed method, the electric-field distribution produced by a waveguide aperture installed in a liquid container is used to calibrate the SAR probe. The field distribution is shown to be the same as that given by a conventional calibration method by analytically deriving a closed-form expression for the field produced by the waveguide aperture with the help of the paraxial approximation. Comparing the approximated and measured distributions reveals that the closed-form expression is valid for the electric-field distribution near the central axis of the aperture. The calibration factor for a commercial SAR probe is evaluated by the proposed method and agrees well with that provided by the manufacturer of the probe.