venerdì 6 luglio 2007

Optimize Wireless coverage for cents.

In this article I will teach how to make a very cheap wireless parabolic antenna from cardboard, tape, and tinfoil. Apart those components you're gonna need Wi-Fi equipment 801.11B-G I doubt this is gonna work on 801.11N because of the MIMO part of the standard.

Instructions are all over the internet, but I had to look hard to find them so I thought I can just put them here with a list of links to interesting places to visit.

  1. With a Reflector you are not touching your original equipment. Warranties stay on.
  2. A reflector can be adapted to be mounted on a Wi-Fi antenna or even on a Wireless Wi-Fi USB adapter.
  3. If you use a reflector and a Wireless USB adapter you can technically move the antenna as far as your extension cable can go. Using powered USB HUBS in between there are been made setups of 30+meters! This is simply impossible using a traditional approach because the wireless signal can't travel along antenna cable without losing strength AND it is WAY CHEAPER.
  4. The reflector works like a mirror for radio signals. It concentrates the signals coming from one direction and stops those coming from the opposite side. Thus It can both secure your wireless AP from being maliciously accessed while providing better coverage where you need it.
  5. It is DAMN cheap.
I present you two of the designs that worked best on my setup. The first one that I introduce is the EZ-10 from This one has proven working best with USB Adapters. The only modification needed was to cut a hole in the center tight enough for the adapter to snug inside.

There are the instructions printed alongside the antenna template. Just print the two images each on a A4 sided sheet. Then apply the scheets on the cardboard (the perfect cardboard is the one from shoe boxes). The square part had then be covered one side with tinfoil. I used aluminium tinfoil myself and acrilic glue. The triangular part is for keeping the reflector in shape and holding it to the antenna. After that glue or stick the thing togheter. If you want to adapt it to a USB stick then be careful not to make too big the hole otherwise it may fall.

The other design is the Windsurfer. I don't know where it does come from but I really like the shape and it has proven to work best on dipole antennas (the ones that come with the Access Points.

The windsurfer design lets you save a little bit on paper cardboard and tinfoil. And it looks better. Aslo it has a slightly better constuction and can withstand bumbs and accidents without losing the shape. Instruction for assembly are basically the same. Please print on A4 size since increasing it does not yeld additional gain.

Action Shots:

9 to 10Db gain to my Access Point.
  • The most interesting place of all is the keybola site. Unfortunately I don't understand their language and there is no "english here" button neither international shipping is provided. Very unfortunate as it looks cheap and effective: here it is.
  • This is another website with lots of graphics about a teacher building reflectors using chinese cookware, interesting to give a look at! Here it is.
  • Netstumbler for Windows is the essential tool in verifying network coverage and best of all it comes free and with GPS support just in case you are planning to wardrive. Here the link to netstumbler.
  • Do It Yourself Antennas. Link to a site full of weird experiments with antennas. Converted Sat Paraboles - Pringles Cans - Antennas made of nets... whatever...
  • Freeantennas - The site offering free antenna templates. I think one of those i present here is from there (The EZ-10). The windsurfer template is catalogued as EZ-12

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