A quick back-of-the-envelope calculation assuming dipole radiation pattern shows you need 3 W XMIT power to get 1 mW/cm^2 at 20 cm. Surely this thing radiates nowhere near that much power?
> From: "Jim Eichner" <[email protected]> > Date: Fri, 28 Apr 2006 13:24:32 -0700 > To: <[email protected]> > Subject: Embedding WiFi into a non-radio product - FCC 20cm rule > > We are looking at embedding an 802.11 transmitter into a product. The > transmitter has an FCC limited modular approval and one stipulation of > that approval is that steps must be taken to ensure the user cannot come > within 20cm of the antenna. I am being told that the 20cm is measured > from any part of the user's body and that this is a firm requirement. >> From what I can tell, most (all?) modular approvals have this > limitation. > > For an end-product that will find use in homes, business, and industrial > locations, ensuring this separation seems difficult if not impossible. > The product is intended for wall mounting, and even at the very top of a > wall or on the ceiling in a house tall people will be able to reach to > within 20cm of the product. Are we really expected to restrict the > installation such that it is not physically possible for someone to come > within 20cm of the antenna?!? > > This isn't a laptop computer or a cell phone - nobody has any reason to > be holding onto it, holding it against their head, or even be looking at > its LED's for more than a few seconds. It seems to me to be overkill > that it can't just sit on the wall like a thermostat for your furnace or > the control panel for your home alarm. Maybe I wouldn't want it mounted > on the wall right above the head of my daughter's crib, but surely > there's a common sense compromise that is compliant? > > If not, is our only way out of this to do expensive SAR testing and > prove that the 1mW/cm2 limit is met? > > Does anyone know if Zigbee also has this 20cm limitation? > > Thanks in advance, > Jim Eichner, P.Eng. > Compliance Engineering Manager > Xantrex Technology Inc. > e-mail: [email protected] > web: www.xantrex.com > Any opinions expressed are those of my invisible friend. > Confidentiality Notice: This email message, including any attachments, > is for the sole use of the intended recipient(s) and may contain > confidential and privileged information. Any unauthorized review, use, > disclosure or distribution is prohibited. If you are not the intended > recipient, please contact the sender by reply e-mail and destroy all > copies of the original message. > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
