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Experts warn of dangers of amplifying WLAN antennae

"It has been warned that exposure to even as little as a 1/4 watt amplified with a 14db antenna, such as described here, could lead to severe vision problems and possibly other health issues.

You really, really don't want to get into mucking about with wireless LAN antennae until you know a lot about what you are doing.

It is possible to massively boost the range of your local wireless network - and if you're serious about doing it, the "how-to" information is here - but the health warning isn't the only one you need to take on board.

For a start, it's worth remembering that most of the "build your own directional antenna" articles you will read, are written by people living in America.

And some of these people live way, way out of range of normal villages and towns, and are trying to reach their neighbours across huge distances. Things may be very different where you live!

Devices like this reflector will turn your WiFi into a directional transmitter, -capable of hugely improving its range, as long as you stay in the beam - and quite probably worth a try if your ambition is to take your PC down the nearest pub. But you need to know what effect this will have on your neighbours.

The idea of "serving a whole neighbourhood by sharing your broadband with them all" is particularly daft for a number of reasons.

For a start, building a real amplifier (this too is covered!) for the antenna is definitely going to be illegal unless (possibly) you have a ham radio licence.

Sharing your internet may not be illegal, but until the law is changed you could, in theory, get pulled up if you charge money for this.

What is more likely to be a problem, however, is that your network will be shared, too. And unless you are really happy for everybody in your neighbourhood to read all your private emails and scan your hard disk for interesting image files and "borrow" your software and infest your LAN with viruses and trojans and, perhaps, even forge emails from you to others ... then more than just a little expertise is needed in setting up network security.

It works the other way, too. If your neighbour has file sharing enabled on their home computer - and most people do! - then you'll be able to see everything they have, when they connect to your network. And you may think "Wow! - cool!" until, that is, they accuse you of having caused their latest virus. Especially if you have.

This isn't going to stop a lot of people experimenting, of course; and out of such experiments, with all their mistakes, a lot of good things like Consume.net may come. But not all the people experimenting on consume necessarily know what they're doing. As the designer of the "pringle's tube" antenna above says:

"Before you run out and do anything, think carefully about what you are doing. You are going to be sending electromagnetic waves through the air. This can cause much distress to folks who are not expecting it, and when they get upset, they will call the authorities. So, you may want be knowledgeable about what you are doing before you do it. Read the rules and regulations. The antenna design I illustrate here is extremely experimental. I have heard that its use could cause interference in near-band frequencies that are commonly used in things such as portable wireless (not cellular) phones that people may have in their homes near you. There are all kinds of wireless devices out there that operate around the same band as 802.11b, and these are potentially disrupted by use of the equipment described here."

And, he adds: "You may consider purchasing an SWR meter and you may excercise much care, consideration for others and caution if and when you go out and spend £600 or more on an amplifier for use with your antenna. I have also heard that if your antenna is too efficient, that you may even damage your 802.11b device with too much current. If you do not know what you are doing, study until you are confident that you will not break people, places or things when you start experimenting."