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. Practically all short-range wireless network use WiFi. Using specialized equipment, Wi-Fi is usable over a very long distance, even over hundreds of miles.

When designing a long-range Wi-Fi link, we must account for the curvature of the Earth.

Wi-Fi uses signals in 2.4 GHz or 5 GHz frequencies which have poor signal penetration. In any long-range Wi-Fi link, one needs to make sure there is a minimal obstacle between both transceivers. The amount of space that needs to be freed as much as possible is called the 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 barrier 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 the 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 real 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.