[sclug] Long distance Wifi

[Bob Dunlop]

Hi,

On Mon, Feb 27 at 07:21, ed wrote:
> > We have a place on a hill in the depths of Wales and would like to get
> > broadband.  Unfortunately we are too far from the exchange to get it 
> > directly although some friends have it in the village down in the 
> > 'valley'.  I was wondering about the possibility of using
> > point-to-point  antenna to do wifi from our friends.  I've seen loads
> > of commercial and  'pringles can' antenna on the web but nobody seems
> > willing to put a  distance on their performance.
> 
> By pringles can, are you referring to 'yagi-uda'? These have better
> performance on ptp networks, you will need one at each end of course.

I have a home made Pringles antenna and by comparison with a commecial
14dBi yagi I reckon it ways in at about 12dBi.  The Pringles can is a
lot more compact and useful when traveling but I'd hate to have to try
and waterproof it.

As for range both were very useful for snooping on the villages WiFi ISPs
traffic at a range of 1-2km.  I live on top a hill and have a good line of
site to the village.

Hi Ed!  do you remember this thorn in your side :)


> > First, is this actually possible?  How far can these antenna work? 
> > Our  closest friends are about 1km away in direct line of sight.
> > Second, is it legal?  How do people like BT view sharing a broadband 
> > line like this?

The ISP that Ed worked for provided me with a nice box on a pole with the
antenna and Ethernet bridge built in to cut down on any lengths of coax
which are very lossy at 2.4GHz.  The antenna was only 9dBi but it easily
maintained a 5.5Mbps link to the church tower 1.2km away.  Such a pity so
much of the ISPs other infrastructure didn't work as well.

BT don't like it but non-commercial sharing is legal.  I think there was
a test case a couple of years back.


> If you can get external bridges (such as smartbridges) you can attach
> the bridge to the antenna mast and keep coax short, the shorter the less
> loss incurred.

I had two Smartbridge airBridge TOTALs that I gave to a community WiFi
project in Southampton which they were going to try and build a point to
point link with.  Unfortunatly the project died before they actually got
to try it.

Ed do you know if the TOTALs can actually be used like this ?

If someone else wants to try it I have two more airBridge TOTALs free to
whoever wants to collect them.  Only one Power over Ethernet injector
though.

-- 
        Bob Dunlop