On Sun, 13 Feb 2005 10:32:18 +0000 (UTC),
(Gordon Henderson) wrote:

In article ,
T i m wrote:
Hi All,

I would like to extend the range of a home WiFi link (better signal
strength down to the workshop) and wondered if anyone here had
*actually* built / tested one of those DIY 'can' type antenna /
reflectors / whatever?

If you don't have true line of sight, then you're shafted.

I sorta do Gordon. From the window in the spare (junk) room I can
clearly 'see' the workshop.

Even with line of sight, theses a thing called the fresnel zone
which extends out in a cone from the direct line of sight. There are
various calculations required to calculate this, but for most domestic
appications, like of sight with a cylinder of a few metres diameter will
give you a good signal.

Understood.

What type of interface makes the job easier (USB 'dongle', remote usb
'compact type' , PCI / PCCard SMA connector etc)?

Forget the USB ones - go for a pair of WiFi Bridges. Preferably ones
designed for outdoor use with power over Ethernet. That way, you just
plug one into the house LAN and the other into the workshop LAN.

Ok ..

I've built community broadband networks with various units - the favourite
is the Smart Bridges range - they have various flat-plat directional
units which are reasonably good in bridge mode, and more importantly,
weather proof and take power over Ethernet. The ones we use are about
7" square.

Is this 'legal' then Gordon. That panel seems likely to gave a gain
greater than unity?

Power over Ethernet means that you just run one cable to the outdoor unit,
and that cable is a digital data cable,

Like USB . didn't know you could get such but it makes sense.

rather than an analogue RF signal,
which at the power levels avalable to you in WiFi applications is woefully
weak and prone to cable, and connector losses.

Indeed ;-(

You can built your own "pringle can" antennae and buy external antennae to
fit onto some units, but then you have the problems of weather proofing
it. You really do want the units outdoors pointing at each other, don't
fool yourself with the advertising blurb that comes with them! You might
get a signal through a wall if the antennae are prepindicular to it,
but at an angle, pythagoras comes into play and the wall sudenly becomes
a lot "thicker" that it might appear...

Understood ;-)

I have one link that 7.5Km long, and it's providing and acceptable signal
for the home user, but they have a rather large grid parabolic reflector
on the chimney of their house pointing back to the base station... So
with care and the right kit, quite a lot is possible.

Hmm, so if you were to 'reflect' (concentrate) the signal would that
stay within the rules? What would be the practical difference then re
using a Yagi?

Saying all that, you might be lucky with ordinary kit - radio waves do
reflect - but they will be severely attentuated by trees with leaves on
-I have some graphs that look great in the winter... Come spring when
the sap starts to rise and you can see the signal strength drop )-:

All concrete here ;-) I *did* have a pretty reliable link using a
Netgear AP to a Netgear USB unit (not dongle) but the AP seems to have
died and a Belkin WiFi router has taken it's place for the moment
running in AP mode.

Drop me an email if you want more details - it's actually been a while
since I looked at the market and devices,

Thanks for the kind offer ;-)

but IIRC we were paying
something like £150 each for the smartBridge units...

Ouch! A bit outside my league I'm afraid .. hence the 'DIY' interest
...

All the best ..

T i m