ID Number		1598
Study Type		Engineering & Physics
Model		Modeling of RF exposure and microwave hearing effects
Details		Numerical analysis of thermoelastic waves excited by absorbed energy of pulsed microwaves (915 MHz) in two MRI-based human head models showed surface heating as important in exciting the fundamental mode of the pressure waves in the head. The peak pressure of elastic waves in the realistic head models is of the same order as the previously reported values obtained with a homogeneous sphere model. A comparison between the strengths of microwave-induced pressure (0.18 Pa) at the perception threshold and ultrasound-induced pressure (7700 Pa) during medical diagnosis revealed that the microwave-induced pressure is more than 42,000 lower. This result suggests that the microwave hearing effect at the threshold level is not likely to be hazardous with regard to the strength of the pressure waves, the dominant force in comparison to restrictive force and radiation pressure. In the abstract, a numerical analysis (FDTD) of microwave hearing in rats using a model developed by Brooks AFB from multiple MRI scans of a Sprague Dawley rat. Assuming a 370 g rat the authors report an SAR of 600 - 1200 W/kg would have to be achieved for microwave hearing to occur. This would translate into a power of 90 Watts from a standard GSM phone antenna. Additional studies are ongoing to examine the effects of short-pulsed microwaves on MW hearing.
Findings		Effects (only at thermal levels)
Status		Completed With Publication
Principal Investigator		Tokyo Metropolitan University, Japan - taki@eei.metro-u.ac.jp
Funding Agency		MIC, Japan
Country		JAPAN
References		Watanabe, Y et al. IEEE Trans. Microwave Theory Tech., (2000) 49:2126-2132
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