Long-Range Wi-Fi and the Curvature of the Earth

Wi-Fi is one of the most common ways of getting connected to the Internet. It is usually used in most short-range local network. But if using specialized equipment, Wi-Fi can be used over very long distance, even over hundreds of miles.

When designing a long-range Wi-Fi link, the curvature of the Earth needs to be accounted for.

Wi-Fi uses signals in 2.4 GHz or 5 GHz frequencies that have poor signal penetration. In any long-range Wi-Fi link, one needs to make sure there is minimal obstacle between both transceivers. The amount of space that needs to be freed as much as possible is the link’s Fresnel zone. The size of the Fresnel zone depends on the frequency used by the link.

The obstacle can be anything. Buildings, trees, mountains, hills, all can obstruct Wi-Fi signals. On a very long-range implementation, the single most significant obstacle is the curvature of the Earth.

Almost all manufacturers of long-range Wi-Fi equipment provide link planning software that will automatically calculate and simulate the required space that needs to be freed between both transceivers. The software does that by accounting for the location of both transceivers, surface topology, the height of both towers, the size of Fresnel zone, and naturally, the curvature of the Earth.

Long-range Wi-Fi is one of those technologies that depend on the knowledge of the actual figure of the Earth.

Planning Software from Various Long-Range Wi-Fi Vendors

These are some links to link planning tools from various long-range Wi-Fi manufacturers. Some of these are free to use, others require free registration.

Reference