| William H. Magill on Wed, 12 Mar 2003 15:39:04 -0500 |
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On Wednesday, March 12, 2003, at 11:33 AM, Kevin Brosius wrote: Along that line... How can I get the maximum range out of a wireless access point and how far is that? I'm interested in omnidirectional signal strength, rather than single line solutions. The transmitted power limit is 1 microvolt per meter at 50 meters. This is an FCC regulation, to which all the manufacturers must conform when they submit their transmitter to the FCC for testing and approval. If the transmitter exceeds that limit, it must be individually licensed, again by the FCC. No modifications may be made to the design without resubmitting the final product again to the FCC for re-certification. This restriction also applies to antennas. That power limit translates into roughly 150-200 feet radius from the antenna where there will be sufficient signal strength to get 10meg from 802.11b -- for 802.11g, cut that radius down to about 50 feet. Of course this in the middle of an open field. Since this is RF, once you start putting "stuff" between the transmitter and the receiver, your signal strength begins to drop, or increase! (Although the increase is rare to non-existant in the 802.11 frequency band.) Much more common is the fact that the RF signal is absorbed by the "stuff" -- some things, like vegetation absorb relatively little. Other things like Masonry absorb a lot. Note that there is also the problem of reflection. Masonry probably reflects and scatters more than it absorbs, while metal surfaces will reflect virtually all. This is the reason that people put receiving antennas on the roof - unobstructed view of the horizon. So the short answer is -- figure on 150 foot max range, with the probability that it will be much shorter. If you get longer range, you are ahead of the game. T.T.F.N. William H. Magill # Beige G3 - Rev A motherboard - 768 Meg # Flat-panel iMac (2.1) 800MHz - Super Drive - 768 Meg # PWS433a [Alpha 21164 Rev 7.2 (EV56)- 64 Meg]- Tru64 5.1a magill@mcgillsociety.org magill@acm.org magill@mac.com _________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.netisland.net/mailman/listinfo/plug-announce General Discussion -- http://lists.netisland.net/mailman/listinfo/plug
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