RF fields and 2-way radios

[Jillian.Wright@dtir.qld.gov.au]

Dear Radsafers,
When tested, vehicles where 2-way antennas were fitted 
on the driver's side fender about 300 mm forward of the 
windscreen had elevated E and H fields produced by 
resonant coupling effects between the steering wheel and 
driver side seat frame. Shifting the antenna to the LHS 
fender made no difference. A vehicle with a bull-bar 
mounted antenna and a truck with a LHS gutter mounted 
antenna (drops the resale value) did not exhibit this effect. 
2-way radios transmitted at a nominal 25W, f = approx 
81MHz.
 
What is the mechanism inducing the fields between the 
seat frame and steering wheel?  and
How else can the antenna be mounted so that these fields 
are unlikely to be generated?
Few vehicles have bull bars.
 
Thank you.
Jill
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Jill Wright, M.H.Sc., B.App.Sc., MSIA
Senior Workplace Health and Safety Inspector
Department of Training and Industrial Relations
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Jillian.Wright@dtir.qld.gov.au
PO Box 317 Annerley QLD 4103 AUSTRALIA
Phone: 61 7 3896 3419   Fax: 61 7 3393 1869
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