Geekcorps Mali launched a project in mid-September to investigate the technical and business aspects of building small, low-cost antennas for the Malian television and WiFi (2.4 GHz) markets.

Editor’s note: As of 7 November 2005, we have published instructions on how to build your own BottleNet antenna.

The do-it-yourself (DIY) antenna designs were based on information gathered from numerous sources, including standard ham radio operator reference manuals, books on building wireless community networks, numerous DIY wireless sites on the Internet, and from the past experiences of GCM volunteers with wireless antennas. Changes to the designs were made to incorporate materials that are easily available in Mali (plastic water bottles, used valve stems from motorbikes, window screen mesh, television and low cost coaxial cables, etc.) to minimize the technical skills needed to build an antenna and to reduce costs.

The first tests of two basic forms of DIY antennas, known in the global wireless community as Cantenna waveguides and biquads, were performed on prototypes assembled in mid-October from materials costing well under 500 CFA ( $1.00) per antenna. While these antennas clearly improved the signal levels observed for wireless connections, their gains with respect to the commercial antennas used as references in these tests could not be quantified.

Further tests made in late October to more carefully assembled prototypes demonstrated that these DIY antennas can provide gains and directionality equivalent to low-end commercial antennas which cost about $40 each within the US. These DIY antennas could satisfy the needs of most of the WiFi antenna market in Mali, as well as, in the longer term, the demands of an important segment of the global wireless antenna market. In addition, minor changes to the WiFi designs would make it possible to produce good quality antennas for receiving television signals in the 2-3 GHz transmission band. These television antennas could address a very large market within Mali itself.

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