Long range 802.11b

Joe · 13th December 2005

Bit of an odd question.

But does anyone know the theoretical maximum distance for a 802.11b link, without hosing the local power substation?
Obviously increasing power output, but how much is legal/safe etc

Thanks,
Joe

Cameron Gray · 13th December 2005

British Radio Authority licensing for the ISM (Instrumentation, Scientific and Medical) band 2.4GHz prohibit transmissions more powerful than 90 milliwatts.

Essentially a traditional wireless card equipped with an 18dBi antenna takes you as close to the legal limit.

Distances with an 18dBi Plannar directional can be up to and including 5Km, direct line of sight.

Joe · 13th December 2005

Ok, thanks, you wouldn't happen to know where I could obtain such an antenna do you?

Thanks,
Joe

iGsys · 13th December 2005

It depends on the type of anntena port you have on the card, you can get a load from eBay, if you have a common port type you can get them pretty cheap. For outdoor use, try and get an antenna with a N type lead, and buy a N type pigtail for your wireless card.

P.S. Cameron, don't the Cisco 350 wireless cards work at 100 milliwatts by default?

Cameron Gray · 13th December 2005

You can have any power card you like as long as the combined power doesn't exceed 90 milliwatt. i.e. they'll have a -2dBi spreader antenna, not a gain boosting one.

jamster · 13th December 2005

http://www.solwise.co.uk/wireless-outdoorantenna-24.htm

Jonsen · 15th December 2005

Is it possible to source american equipment from say ebay which is more powerfull than the standard UK? I knew this was possible with those mini walkie talkies.

jamster · 15th December 2005

I imagine it's possible (I think certain AP's can be boosted by themselves to run at higher than the legally prescribed limits, for example the Linksys WAP54G / WRG54G can be made to do so with 3rd party firmware such as sveasoft).

However afaik it's not just a case of 'it's not legal to sell equipment transmitting at above 18db', it's actually not legal to use it. Unless anyone knows otherwise?

Cameron Gray · 16th December 2005

Anyone using equipment above the regulated limit for the 2.4Ghz ISM band is guilty of violating section 6 (I think) of the Radio Telegraphy Act, which has been rolled into the Communications Act (2000).

Typical penalty is £5000 fine, and 12 month suspended sentence.

Same applies for using equipment not in either the 2.4GHz or 5.4 GHz ISM bands without a license to do so.

Jonsen · 16th December 2005

Quote:

Originally Posted by Cameron Gray

Anyone using equipment above the regulated limit for the 2.4Ghz ISM band is guilty of violating section 6 (I think) of the Radio Telegraphy Act, which has been rolled into the Communications Act (2000).

Typical penalty is £5000 fine, and 12 month suspended sentence.

Same applies for using equipment not in either the 2.4GHz or 5.4 GHz ISM bands without a license to do so.

So all these people buying walkie talkies on ebay could face a £5k fine. Ouch. How exactly is it policed though? They cant exactly go around every house in the country checking that their wifi is inside the certain guidelines

Jonsen · 16th December 2005

Edit : Please delete, is it possible to delete our own posts because I seem to be in the habit of posting more than once with the same thing.

Cameron Gray · 16th December 2005

If anyone complains of interference, they will investigate and feel your collar or if you are near an RA "listening station" and they pick it up same result.

Most arrests/fines are due to complains of overlap or interference. They will definately do something if you "leak" onto the licensed band either side of the ISM bands.