> Date: Wed, 18 Mar 98 12:25:25 -0800 > From: [email protected] > Subject: Re: RF Exposure > To: "Kathy (Kate) M. MacLean" <[email protected]>, > [email protected], [email protected], > [email protected] > Cc: "'Dr. Jacek Wojcik, Spectrum Sciences Institute'" > <[email protected]>, > "'Dr. Paul Cardinal, APREL Laboratories'" > <[email protected]>
> > --- On Wed, 18 Mar 1998 13:00:51 -500 "Kathy (Kate) M. MacLean" > <[email protected]> wrote: > > Robert - > > > Saline only has been proposed (is not common) as a simulation for > > body tissue (muscle), for which the SAR exposure limit is 4 W/kg. > > For brain and organs, the limits are more strict, at 1.6 W/kg. The > > exact content of the simulation liquid will determine its > > permittivity and conductivity, which need to be different at > > different frequency ranges. > > > Note that for certification purposes, a maximum error of 20% for the > > whole system (liquid, probe, positioning, etc, etc) is now being > > required by the agencies. This is *very* tight in SAR measurement. > > > Please see my earlier post for more information. > > > Regards, > > Kate > > APREL Laboratories > > (.sig at end of post) > > > > > Looking for a supplier of mannequins (head, upper torso, > whole body?) to simulate and measure the absorption of RF energy > from very close emitters (cell phones, man-pack radios, > telemetry). > > > > > Anyone have any leads for anything from raw materials to > complete dummies? > ___________________________________________________________ > > Kate: > > I realize that this is a bit of a drift from my original request > about mannequins and absorption simulation. One of our engineers > here said that he had read that the most affected body component > (he> Is this true, or do you have more heating effect (from a > typical cell phone type emitter) on ear lobes and/or scalp? > > -------------------------- > Ed Price > [email protected] > Electromagnetic Compatibility Lab > Cubic Defense Systems > San Diego, CA. USA > 619-505-2780 > Date: 03/18/98 > Time: 12:25:26 > -------------------------- Hi, Ed - One of the myriad functions of the cerebro-spinal fluid is to dissipate heat away from the grey and white matter of the brain and spinal column. Low-level heating effects on this tissue, therefore are not the most critical issue. (Heating of the grey and white matter themselves would be a bigger point.) In numerical modelling methods, it has been shown that between and quarter and half of the RF energy dissipated by, say, a cell phone, is expected to be absorbed by the ear; however, this involves certain assumptions with respect to proximity modelling which may not always hold (I would refer you to Eistein's comment about reality and mathematics... :-)). This is not seen in direct SAR testing, partly because of the real behaviour of the antenna feed point. In any case, although we do not make a distinction between the "head" and the "brain" in regulatory limit setting, it could be argued that the ear and skin are "muscle"-type tissue, as opposed to "organ"-type tissue, and therefore less susceptible in general. Regards, Kate PS - We are planning another workshop in the "Demystifying..." series for RF exposure and for SAR, to be held in mid-late April. Let me know if you'd like to know more! ___________________________________________________________ Kathy M. MacLean, President APREL Laboratories "Research-Training-Consulting-Testing Wireless-EMC-Acoustics-Health & Safety/SAR" 51 Spectrum Way, Nepean, Ontario, Canada K2R 1E6 Tel (613) 820-2730; Fax (613) 820-4161; Cell (613) 791-3777 email [email protected] http://www.aprel.com
