Cantenna

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

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

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. [Hutchinson, Chuck. (May 1984). "Heathkit Cantenna, Model HN-31A". "QST". p. 42.]

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. [ [http://mali.geekcorps.org/2005/11/07/how-to-make-a-bottlenet-antenna/ Cantenna build on a pole (includes construction plans)] ]

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.

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 [ [http://www.thedropzone.co.nz/cantennacal.htm Optimal cantenna dimensions] ] [Antenna Theory: Analysis and Design by Constantine A. Balanis]

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-antennas, quad-antennas and biquad-antennas [ [http://www.heise.de/netze/WLAN-Richtfunk-mit-Hausmitteln--/artikel/100565/0 WLAN-Richtfunk mit Hausmitteln - Worauf es beim Selbstbau einer leistungsfähigen Richtantenne ankommt] -Article describing the use use of Yagi, quad and biquad-antenna's with WiFi dongles)] 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 [ [http://www.freeopenbook.com/wireless-hacks/wirelesshks-chp-4-sect-23.html Wireless Hacks book by Rob Flickenger (open-source version)] ] For extra references and pictures, the Instructables websites may be used. [ [http://www.instructables.com/id/Yet-another-laptop-wifi-antenna-mod Instructables DIY Cantanna/antenna pictures] ]

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, [ [http://www.makezine.com/blog/archive/2006/10/cantenna_diagra.html MAKE: Blog: Cell phone - Cantenna diagram and parts list ] ] improving reception and decreasing noise.

In popular culture

The webcomic "xkcd" references cantenna in the comic " [http://xkcd.com/466/ Moving] ". A geek couple connect through a cantenna in an attempt to access the Internet after moving apartment.

See also

* FON#La_Fontenna, a omnidirectional, cheap and high power antenna to distribute internet access around the world using a series of wireless LAN's
* WokFi antenna
* WarXing

External links

* [http://www.youtube.com/watch?v=KN_1oe3z7EQ Youtube video on How To Build A low loss Cantenna]
* [http://www.turnpoint.net/wireless/cantennahowto.html How To Build A Tin Can Waveguide Antenna]
* [http://www.saunalahti.fi/elepal/antenna2.html Wlan antenna Waveguide type]
* [http://www.oreillynet.com/pub/wlg/448 Antenna in a Pringles can]
* [http://www.binarywolf.com/249 Do-It-Yourself Wireless Antenna Update]
* [http://kioan.users.uth.gr/wireless/cantenna/ Cantenna Calculator]
* [http://www.cantenna.com/hotzone.html How to Connect to Free Public Networks with a Cantenna]
* [http://www.rfshop.com.au/ContactUs/Bloggs/tabid/648/EntryID/2/Default.aspx Designs for 2.1GHz, 2.45GHz, 3.5GHz, and 5.8GHz cantennas]
* [http://www.networkgarage.com/2006/07/extend_your_wireless_range_wit_1.html Extending Your Wireless Range with a Cantenna]

References