How to Build a Tin Can Waveguide WiFi Antenna

The basis for increased Wi-Fi gain.

Tin can waveguide antennas have been Do It Yourself projects since 2003, beginning with the Pringles can antenna. Improvements were made, getting greater signal boosts with larger containers up to the 42-ounce juice can, and later using a USB cable for connection to the computer rather than the coaxial cable. That's because a coaxial cable suffers signal strength losses over distance, and requires both a pigtail and a connection to an external connector on a Wi-Fi card. The USB cable has no signal loss, and no extra cable or computer cards are needed.

Things You'll Need

• Juice can
• BNC connector
• Power drill
• Drill bits
• Solid wire, 12-gauge
• Deburring tool or round metal file
• Soldering iron
• Solder
• USB Wi-Fi adapter
• USB cable
• Altoids can
• Razor blade
• Spacer
• Rubber foot

Instructions

The Juiciest Way to Free Wi-Fi

1. Find an empty 42 oz., 4.25-inch diameter juice can.

2. Completely remove one end of the can and clean the can thoroughly with soap and water.

3. Measuring from the outside closed end of the can, make a mark 1.625 inches down.

4. Punch an opening in the can at your mark with an awl or a nail. Use a drill to enlarge it to fit your connector. The final size of the opening will depend on your connector. Use a round file or deburring tool to remove any remaining metal flanges.

5. Measure the 12-gauge wire as near to 1.21 inches as possible, including the length of the connector end within the can. The wire should not extend more than halfway into the can. Too long a length impairs reception.

6. Using small pliers, modify the BNC connector by removing the metal sleeve to expose the plastic hub. File any remaining rough spots.

7. Punch a hole through the plastic end of the BNC connector.

8. Push the length of 12-gauge wire through the BNC connector, then put the connector aside.

Prepare the Wi-Fi Adapter

1. Buy or use an external USB Wi-Fi adapter.

2. Remove the plastic case. There is generally one screw on the bottom under one of the rubber feet. Use a razor blade or knife to remove any paper covering the seams.

3. Separate the cover and remove the circuit board and attached antenna.

4. Use a razor blade to carefully remove the plastic covering and expose the bare antenna wire.

5. Detach the antenna, leaving only the coaxial cable length to solder to the antenna element in the BNC connector.

6. Put a little rubber self-adhesive foot on the opposite end of the circuit board from where the screw will attach the board to the Altoids box. Test the fit of the altered Wi-Fi card circuit board in the Altoids box, making sure the board is not in contact with the metal bottom of the box.

7. Take the circuit board out of the Altoids box and put it aside temporarily.

Final Assembly and Connection

1. Secure the assembled BNC connector with the threaded end up through the Altoids box. Tighten the bolt on the connector to secure it within the Altoids box.

2. Solder the Wi-Fi card's remaining coaxial cable to the element in the BNC connector end within the Altoids box. This wire may be cut to fit if it's too long.

3. Plug the USB "B" end (the smaller squarish USB plug) through the hole in the side of the Altoids can and plug it into the adapter USB port on the Wi-Fi card.

4. Connect the USB "A" end of the cable to a USB port on your computer.

5. Position the juice "cantenna" for strongest reception. Enjoy increased signal strength of 15dB or more.

Tips & Warnings

• The modified Wi-Fi adapter is the heart of this project. It eliminates the need for a separate Wi-Fi card in the computer and the pigtail interconnect cable, and does not suffer the signal loss that occurs with coaxial cable. For even greater cable length and robustness, use a Cat-5 ethernet cable to connect to the computer instead of the USB cable.

References

• amateurlogic.com: Building an Improved Juice Can Cantenna
• turnpoint.net: Tin Can WiFi Antenna Instructions