How to Build a Cantenna
As promised, I am now posting pictures and instructions that I used to build my cantenna. As always, if you injure yourself or damage your equipment, or get in to any kind of trouble, I cannot be held responsible. Do at your own risk!
Things you'll need:
A wireless adapter with an external antenna port
- An N-femail connector
- 2 inch, 12-gauge copper wire
- 4 #6, short screws
- One can
- A drill, or a nail and hammer with some patience.
- Solder and a soldering iron.
Step 1: Get a wireless card that has an external antenna connector. These are surprisingly hard to find. Check out E-bay, there are several Orinoco, IBM Wavelan, or Buffalo PCMCIA cards that will do the trick.
For the brave, you can also modify several existing cards or USB devices to create an external antenna connector. This is what I chose to do. I have a Linksys WUSB11 wireless USB network adapter. If you pop it apart by removing the screw under the top left rubber foot (voiding your warranty of course), there is an MMCX connecter that is used to connect the existing antenna. (on versions 2.5 and above, previous versions you will have to buy a connector and solder it in yourself.) Just disconnect the antenna from the connector, and you have a nice port you can use for your cantenna.
Step 3: Buy an "N Connector". You can buy these all over the place online, or in some electronics stores. I just bought mine on E-bay. Get one with the mounting holes so you can mount it to your cantenna.
Step 4: Buy a "pigtail" that you will use to connect your wireless card to your cantenna. Remember that different adapters have different types of connectors. One side needs to be an N-mail connector and the other end needs to be whatever you need to match your card. Just do a Google search for connector information for your card if you are unsure what type to get.
Step 5: Drill the holes for the connector. The distance from the back of the can must be as close to 1.78 inches as possible.
Step 6: Solder the copper wire into the N connector. Then cut the wire so that the length of the copper wire and the holder on the N connecter is as close to 1.21 inches as possible. The portion that sticks into the can altogether should be 1.21 inches.
Step 7: Insert the connector into the hole, and put the screws in. The screws should barely enter into the inside of the can. If your screws are too long, get some shorter ones or use some washers on the outside of the can to shorten them up.
Step 8: If you want to weather proof your cantenna for outdoor use, you can paint the outside and put a plastic lid over the cover. Make sure this lid will not block the radio waves that pass through it! I read somewhere that you can test whether it will block the waves by putting the lid in the microwave with a glass of water next to it. When you run the microwave, the water should get warm, but the plastic lid next to it should not. If it does, then do not use the lid. I used a lid from a La Choy Chow Mein Noodles can.
That's it! You have just learned How to Build a Cantenna Now just connect your wireless adapter to your cantenna with your pigtail and test it out. Use a program like NetStumbler to test your increased signal strength. Remember that the power of the antenna is doubled for every 3 dBm increase. (Notice that it will show the signal like this: -77. Therefore the higher the number (the less negative) the number gets, the better the performance.
Just remember that the measurements need to be as close to exact as possible. At 2.4Ghz, small variations make a big difference.
- How To Build A Tin Can Waveguide WiFi Antenna The most popular and very informative cantenna building site. Go here to use the calculator if you would like to use different sized cans.
- Spreadsheet that has different sized cans and their calculations along with the optimum can size calculations.
- FreeAntennas.com has great information on making reflectors for your AP. Easy to and cheap (practically free) to make and provide increased signal strength.