nanog mailing list archives
Re: wanted: wireless magic tricks
From: Greg Maxwell <gmaxwell () martin fl us>
Date: Thu, 16 Aug 2001 13:28:46 -0400 (EDT)
On Thu, 16 Aug 2001, Leo Bicknell wrote:
On Thu, Aug 16, 2001 at 12:57:19PM -0400, Greg Maxwell wrote:FCC Part 15.247 limits EIRP. You can't legally put out enough power in the unlicenced bands.Sure you can, you get more power with more directional antennas. Here's a company that will sell you everything you need: http://wavewireless.com They can get 25 miles. Using a 36db Yagi you can build the same thing yourself, as many have done. You do have to back off the transmitter slightly to stay within FCC limits, but 20+ miles 802.11b is easily done within FCC limits. I cannot speak to 802.11a, as I know nothing about how it works, or the frequences and power involved.
Directional antenns increase effective power output. FCC has limits not only on transmitter power but also EIRP. A 36dBi with 100mw input will yeald an EIRP of over 220 watts, well above the limit of sanity and the law for EIRP of unlicenced equipment in the ISM band. You'd have to back off to less then 2mw to remain in the legal limits. I just ran some quick numbers, and a unlicenced 20mile link like that would be possible, but I wouldn't sell it.: 1.75mw -> 36dBi antenna -> freespace -> 36dBi antenna -> reciever + mis losses, has an EIRP of about 3.9 watts (legal). You'd have about 15db of link margin, and that's much too little for a reliable link IMO.
Current thread:
- Re: wanted: wireless magic tricks, (continued)
- Re: wanted: wireless magic tricks Greg Maxwell (Aug 16)
- Re: wanted: wireless magic tricks Joel Jaeggli (Aug 16)
- Re: wanted: wireless magic tricks Curtis Maurand (Aug 16)
- Re: wanted: wireless magic tricks Charles Sprickman (Aug 16)
- RE: wanted: wireless magic tricks Dennis Dayman (Aug 16)
- RE: wanted: wireless magic tricks Greg Maxwell (Aug 16)
- Re: wanted: wireless magic tricks Matthew S . Hallacy (Aug 16)
- RE: wanted: wireless magic tricks Greg Maxwell (Aug 16)
- Re: wanted: wireless magic tricks Leo Bicknell (Aug 16)
- Re: wanted: wireless magic tricks Greg Maxwell (Aug 16)
- Re: wanted: wireless magic tricks Leo Bicknell (Aug 16)
- Re: wanted: wireless magic tricks Greg Maxwell (Aug 16)
- Re: wanted: wireless magic tricks Leo Bicknell (Aug 16)
- Re: wanted: wireless magic tricks Greg Maxwell (Aug 16)
- Re: wanted: wireless magic tricks M. David Leonard (Aug 16)
- Re: wanted: wireless magic tricks Craig A. Haney (Aug 16)