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Homemade WLAN Antenna

If the most important place in your office or apartment gets only poor WLAN coverage from your router (i.e. due to walls), here's a simple way to tune the antenna of the router to become a directional Yagi-Uda antenna which you can point exactly at that critical place. You can do this with any router model as there's no need to alter the router antenna itself in any way.

All you need is some leftover Styropor, roughly 35cm of solid copper from leftover electrical cable and a little spare time. The procedure is explaned in great detail in this article from Heise Netze. Here are some translations for those who don't know any German. Or maybe you prefer a good laugh reading the article translated with Google.

Positions and lengths of the copper bars relative to the router antenna:

Length in mm50.051.051.552.053.060.0
Position in mm1228857319-25

Most important hints:

  • Use solid copper with roughly 1mm diameter. If no copper is at hand, another metal will do, yet you loose some efficiency.
  • If you use thicker copper, reduce the length of the bars by 1mm (for a diameter of 1.4mm) or by 2mm (for a diameter of 2mm).
  • Align all copper elements centered with the antenna of the router. It's sometimes hard to tell where the exact center of the router antenna is, so try different positions and measure how the signal strength behaves.
  • If you have more than one antenna on the router, equip just one with this piece. WLAN clients will automatically talk to the antenna which offers the highest signal strength, so you can use one as a directional antenna and leave the other for coverage closer to the router.
  • This won't work with 801.11a nor i.
  • Make sure you know the rules concering radio communication in your country. You might have to reduce the output power of the router to 25% in order not to exceed limitations and risk prosecution.

(Sven Schwyn)

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