re: Microwave oven and battery

[jillian.wright@detir.qld.gov.au]

Hi Radsafers,
 
The respondees are right to be searching for another mechanism for hea
ting of the battery other than the RF fields from the microwave oven.
 
For a microwave oven operating normally (door not warped, no corrosion
 or other substantial damage) the leakage of energy should be no more 
than about 5 mW/cm^2 at 5 cm distance. 
Depending on where the user stands, at that level of leakage, the powe
r density at 0.3m is less than 1.5 mW/cm^2 and at 1m is about 0.01mW/c
m^2.
 
It would be extremely unlikely for a battery in a pocket exposed to 1.
5 mW/cm^2 to couple to the fields with sufficient efficiency to percep
tably heat up. Plus, if a D size battery is 5 cm long it will couple w
ith considerably less efficeincy than an object at the (approximate) r
esonant length of 12 cm.
 
Jill Wright 
Senior Inspector (Non-ionising radiation)
Department of Employment, Training and Industrial Relations
Queensland,  Australia
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