[Techtalk] Tell me I'm dreaming

[Maria Blackmore]

Hi,

You're not dreaming :)

On Tue, 17 Sep 2002, Davis, Jennifer wrote:

> I was just wondering if there is a way to set up a wireless network that
> would have a 750m - 1.0km range (Affordably)?

Easily, the systems we use at work for the wireless broadband stuff have a
range of better than 6 km

> I have a group of about 5 friends all in my neighbourhood and I
> thought rather than all of us spend $50.00 for a high speed connection
> which would keep us on line only when we are near a wire, we could
> share one bigger pipe and be on line with wireless modems.  We're
> talking 5, 6 & 8 blocks away.  My place is the furthest one to the
> west.  It may have been more feasible if I was in the centre.

If you have to have the pipe yourself, then it does cause problems, but by
no means insurmountable :)

What you need is an omnidirectional antenna that is fitted with reflectors
to alter the response to turn it into an antenna that is kind of
directional, but with a very large beam angle.

At work we have a omnidirectional antenna on the roof, with a 6 dB gain, a
7 degree "lookdown", and a single rod reflector to turn the response
pattern into a kind of heart shape (in one direction there is nothing but
farmland except for one town which is covered by its own high gain
directional antenna), it sounds like you will need something similar.

A quick google (http://www.google.com/search?q=2.4GHz+antenna) seems to
throw up a few likely looking plans to build a suitable antenna, and if
you can't find anything on reflectors, let me know and I'll see if I can
turn up something to help.

At the remote locations, I would imagine that the infamous pringles can
antenna, or a variant of would be best, so that you get a nice strong
gain towards the base station.  My preference would probably be one of the
coffee can designs (waveguide style antenna), with a plastic cap on the
end to keep it nice and weather proof.

At the base station, you will need some sort of commercial base station so
that the whole thing can run in "infrastructure mode", and at the remote
stations then any sort of 802.11b card that you have will do the job just
nicely.  Also, don't forget WEP and allow access from *only* the MAC
addresses of the remote stations, and I would really really strongly
recommend a Linux or FreeBSD machine at the base station running FreeS/WAN
(sp?) and then running IPSEC over the wireless links.


> Most of the products I have seen are in the 100m range.  It does seem like I
> am wasting my time pondering this, but if there is a way, I would like to
> figure it out.

There is very much a way, and we make actual money out of something not at
all dissimilar to this.

Good luck :)

If there's anything I've been a bit fuzzy on or want to ask anything
about, please feel free to email me privately or on the list :)

Maria