Cantenna

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A "cantenna" is also a brand name for a dummy load.

A cantenna.

A cantenna is a directional waveguide antenna for long-range Wi-Fi used to increase the range of (or snoop on) a wireless network.

1 Origin of the name
2 Construction
- 2.1 Example of a frequently used construction
- 2.2 Other constructions
3 Usage
4 See also
5 External links
6 References

[edit] Origin of the name

The term 'Cantenna' originally referred to a product sold by Heathkit Co. in Benton Harbor, MI, USA. It was a 50-ohm resistive load used by radio amateurs.^[1]

Cantenna dummy load suitable up to 30 MHz and up to 1 kW

[edit] Construction

Although the original design was based on a Pringles potato chip can, a cantenna can be made from various cans/bottles. These include antennas on both the ground and antennas heightened by means of a pole. ^[2]

[edit] Example of a frequently used construction

A commonly used construction - which is quick, easy, and inexpensive due to use of readily obtained materials - is as follows:

Four small nuts/bolts;
A short length of medium-gauge wire;
A tin can roughly 8 cm (3.66 inches) in diameter, such as a Pringles canister. The longer the better; and
An N-Female chassis mount connector, available at many electronic supply stores.

In the Wireless Hack-book, a alternative to this construction can be made, called the 'Spider Omni', which is even more potent. ^[3]

[edit] Other constructions

The best cantennas are made using a can which has the right measurements. These measurements are in the range of

149,3mm length for a 84mm diameter can
128,2mm length for a 90mm diameter can
110mm length for a 100mm diameter can
101mm length for a 110mm diameter can ^[4]^[5]

Additionally, the use of a pole or other method of elevation also increases the range tremendously and could be added to the can. Also, other antenna-designs using WiFi dongles may be created (notably omnidirectional, sectoral and yagi-antenna's, quad-antenna's and biquad-antenna's ^[6] and waveguides and parabolic dishes. At present, the most potent antenna for its size is the waveguide. Several documents have been open-sourced to create the different antenna's diy, with one of the most popular (open-source) book now being the Wireless Hacks by Rob Flickenger ^[7] For extra references and pictures, the Instructables websites may be used. ^[8]

[edit] Usage

While cantennas are useful for extending a wireless local area network (WLAN), the tiny design makes them ideal for mobile applications such as wardriving. The design of the cantenna is so simple that it is often the first antenna WiFi experimenters learn to build. Cantennas can even be used to increase cell phone range,^[9] improving reception and decreasing noise.