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Spring 2005
A revised 802.11 antenna. Has a higher SNR and a better sized waveguide by using a Pirouette cookie can. This is a full instruction on how to build the cantenna.

:. Project / A Revised Cantenna

First off, let me say that the design is blatantly ripped off the SeattleWireless website.  All I really did was take step-by-step pictures and make a few alterations to fit my needs, as some of the stuff they mention is hard to find.  With that said, this Cantenna is excellent for beginners.  It's easy to build, takes very little time, it's cheap, and offers great gain.

This antenna will plug directly into your wireless card, assuming you have a wireless card with external antenna connectors.  Almost all desktop (PCI) WiFi cards have the external antenna connectors.  If you have one of these, verify that you can unscrew the antenna on the back of your WiFi card.  If you have a laptop with built in wireless, this article is not for you UNLESS you go buy a separate wireless card.  Cards like the Orinoco Silver are pretty cheap online and will offer you much greater signal range than the card/antenna built into your laptop.

Finally, these antennas are really easy to build.  The length of this is due mostly to the fact that I explain every little detail so even a trained monkey could follow it.

Construction Time:

About 30 minutes

Materials Needed:

Item Cost Where at Pictures
A WiFi card with antenna connector (more information) $15-$60 Lots of places online, desktop cards available in stores like BestBuy Orinoco
Netgear
Linksys
Pirouette Cookies $6 Local Grocery Here
4 to 6 inch duct adapter $4 Home Depot Here
about 2" 12 gauge copper wiring $.50 for 1 foot I got mine from leftover dog fencing.  You can buy this at Home Depot none
Cable + connector (more information) $15 SharperConcepts Here
Set of 4 #4-40 x 1/2" flat head nuts and bolts $1 for a package of 8 Home Depot none

Total cost (excluding wireless card): ~ $26.

Equipment Needed (you should have most of these):

  • A good drill
  • 1/2" to 5/8" drill bit
  • Small drill bit to fit the #4-40 bolts / go through the connector holes
  • Soldering iron (with solder, of course)
  • Can opener (preferably one that leaves no sharp edges)
  • Either a drill attachment to strip paint or some low-medium grit sandpaper (somewhere in the 50 to 150 grit) and a little effort
  • Fine point black marker
  • Ruler with millimeter markings
  • Wire stripper/cutter

Construction:

DON'T PANIC.  The length of these instructions is deceiving.  Many of them are very small and take virtually no time.  I promise you can build the entire unit in half an hour and without effort and basically without thinking.  I included a large number of pictures to show exactly what I mean by each step.

  1. Open the cookie can and pull out all the cookies and packaging.  You might want to start off by eating some cookies if you haven't already.  I recommend placing them in vanilla ice cream:

  2. Clean out the cookie can if there are any crumbs or anything in it.  You can wash with water, but make sure it's completely dry before proceeding.

  3. Remove the bottom of the can with the can opener.  If there are any sharp edges or anything sticking out after you're done, use a file to get rid of as much of it as possible.  I used an electric can opener and didn't run into any problems:

  4. Place the lid back on the cookie can.  Measure 44mm down from the top of the can and use the marker to mark that spot.  Make sure its exactly 44mm.

  5. Get out your 1/2" or 5/8" drill bit and drill directly into the center of where you just marked.  Put the connector from the cantenna kit into the hole.  If it doesn't fit, use the drill bit for the next size up.  I didn't have a 1/2" drill bit, so I used the 5/8".  Try not to deform the can while you do this.  If it does become deformed, you can try to roll it back into a cylinder with your hands.

  6. Place the connector in the center of the hole you just created.  The flat part with bolt holes should be on the outside.  Align the connector into the center by looking into the can.  Once it's in the center, hold it there and mark where the four bolt holes line up on the outside of the can using the marker.

  7. Use a drill bit that will just barely fit through the four bolt holes on the connector.  You want it large enough to allow the bolts through but small enough that it fits the holes for the connector.  Drill the four holes where you just marked.

  8. Strip the paint around the holes using the drill adapter or some sandpaper.  Also, smooth out any rough edges (with a file or another adapter)

  9. If your copper wiring is insulated/shrink wrapped, use a wire stripper to get the bare wire.

  10. Make sure the wire is as straight as possible.  Tip: use the drill to analyze how straight it is and help you straighten it out.  Place the wire in like it were a drill bit and tighten down the key on the drill.  Start up the drill, and if you see wobbling in the wire, you can locate bends in it.  Also, by tightening down the drill onto the wire, it will help straighten it out.  Move the wire up and down, tightening the drill in as many places as possible and you'll straighten out the wire almost perfectly.

  11. Solder the wire into the hole on the connector.  I had a hard time soldering it directly into the connector, so I pushed it down and soldered it ONTO the connector on the outside.  This is fine, but there was excess solder.  We want the solder to be as low profile as possible, so I used sandpaper to eliminate some of the excess.  Warning:  If you've never soldered anything before, COPPER CONDUCTS HEAT VERY WELL!!  If you're going to hold onto the wire, use a garden mitt or something or you're going to burn your fingers before you know it.

  12. Measure from the base of the gold nub up 31 mm.  Mark this place and cut it using your wire cutters.  (image via the SeattleWireless page)

     
  13. Bolt the connector into place so that the wire comes into the can.  Put the lid back on the end and attach the 4" to 6" duct adapter on the other end.  Screw the pigtail into the connector and run it into your wireless card.

That's it.  The finished product:

Tips for use:

  • Use NetStumbler to see what networks are available.

  • This antenna is directional, meaning it receives signals in the direction that you point it.  Try doing a full 360 degree sweep (slowly) to see which direction each network is in.

  • Once you've found the network you want to connect to, raise the antenna slightly.  Usually, you're able to receive a signal better by shooting slightly above the target.

  • Typically, the antenna works better at night, due to atmospheric conditions.

  • Unauthorized use of other people's connections is illegal in most places (disclaimer).  But it would be pretty damn difficult for anybody to trace a connection back to you (truth).  If you are going to use somebody else's connection, don't be a dick about it (common sense).

  • Take into consideration what the connection will go through (air, water pipes, high current electric wires, trees, hills, etc).  An external antenna offers the extra advantage that you can relocate it if there's something small in the way that will cause signal loss.  Experiment with location / angle for the best results.

Questions / comments / concerns:

Email: s h a n e [at] eskibarsDOTcom
AIM: eskibars