Biological Tissue-Equivalent Agar-Based Solid Phantoms and SAR Estimation Using the Thermographic Method in the Range of 3-6 GHz

Teruo ONISHI
Ryo ISHIDO
Takuya TAKIMOTO
Kazuyuki SAITO
Shinji UEBAYASHI
Masaharu TAKAHASHI
Koichi ITO

Publication
IEICE TRANSACTIONS on Communications   Vol.E88-B    No.9    pp.3733-3741
Publication Date: 2005/09/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.9.3733
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility(EMC)
Keyword: 
solid phantom,  broadband,  FDTD method,  SAR,  thermographic method,  heat conduction equation,  

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Summary: 
In this paper, the electrical constants of a biological tissue-equivalent agar-based solid phantom from 3.0 to 6.0 GHz are described. The developed phantom can reproduce the electrical constants of biological tissues from 3.0 to 6.0 GHz, and it is not necessary to change the phantom for each frequency band in the range of 3.0 to 6.0 GHz during the measurements. Moreover, adjustments to the dielectric constants of the phantom at 3.0, 3.8, 5.2, and 5.8 GHz are presented. The constants of this phantom can be adjusted mainly by using polyethylene powder and sodium chloride. The phantom can be used to evaluate the Specific Absorption Rate (SAR) as well as the antenna characteristics in the range of 3.0 to 6.0 GHz. Furthermore, the effect of the electrical constants of the phantom on the SAR is investigated. The investigation of SAR measurements is performed on the phantom at 5.2 GHz using the thermographic method. Calculations using the FD-TD method and the finite difference method based on the heat conduction equation are carried out in order to evaluate the thermal diffusion in the measurements using the thermographic method. The measured and calculated results are in good agreement. There is evidence that the thermal diffusion influences the SAR estimation at 5.2 GHz more than in a lower frequency range even though this method basically does not depend on the frequency.