Water Bottle Antenna

In developing nations there's are big problems wiring up your laptop to the network. There are two fundamental causes:

1. The power grid is unstable and often unavailable
2. Many areas lack a terrestrial data connection

But even basic Wi-Fi is a real problem due to the scarcity of essentially all involved hardware. As with all engineers, scarcity is the step-mother of invention. In this case, a plastic water bottle is used to make a dielectric resonator antennas (DRAs.) These liquid dielectrics can be used effectively at frequencies between 1-4 GHz.

What they're doing at BottleNet is finding bottles with the correct dimensions to use as a waveguide. The diameter of the cylinder largely determines what frequencies the antenna can transmit or receive. This is a mathematical relation to the cylinder's length so calculations must be made to cut it to the correct legnth. More here.

But plastic can't reflect microwaves right? Well yeah, that's a bit of a problem. But appropriately size-cans are in short supply. So these little geniuses just wrap the puppy in a wire mesh called fly-screen so it has a reflection profile. The mesh has a 1-millimeter weave which in comparison to the wireless frequencies is effectively the same as a solid reflective metal surface.

Mali must be a nation of a million MacGyvers. Here's what you'll need to do this at home for materials and tools. The final product actually functions on par with a typical low-end factory made wireless antenna. Full instructions here.

MATERIALS
(1) 1.5 litre bottle of Diago mineral water
(1) Piece of metal woven flyscreen 300 mm x 220 mm
(1) Piece of metal woven flyscreen 100 mm x 100 mm
(1) 31 mm length of 14 or 16AWG wire
(1) Appropriate connector (N-type typically)

TOOLS
Pliers
Awl or pointy object
A soldering iron and solder
Scissors for cutting mesh
Leather gloves for handling sharp edges of flyscreen