Technology Review reports on a new lens that can be mounted on, say, the top of a moving train to gather and distribute broadband signals from satellites. Internet access can make a train trip far more productive and enjoyable. But train-mounted satellite dishes that send and receive data can't be used on a lot of routes, as the standard hardware is too big to fit in some tunnels. Now researchers at the University of York, in England, have developed an alternative: a dome-shaped plastic lens that's less than half as high as a typical satellite dish. [...]
With a traditional satellite system, a separate dish is required for each satellite, and the whole dish has to move to track the signal. Moving an entire dish is fine if it's mounted on a stable structure, such as the roof of a house, but not if it's affixed to the side of a train that's running through tunnels and under bridges. A lot of room is required around the device at all times, to ensure that it doesn't hit something while tracking a signal.
With Thornton's device, incoming radiation bounces off the surface on which the lens is mounted. The lens concentrates the reflected radiation to a single point on its surface, where it's collected by a motorized antenna called a feed. To track the signal, only the feed needs to move, as opposed to the entire dish in a conventional system. Moreover, several feeds can roam around the surface of the lens at once, collecting signals from satellites in different locations. [...]
Thornton says that 3G currently doesn't have the kind of geographic coverage required for continuous Internet access along train routes. Upgrades to the cell network, he says, tend to be concentrated in towns. "Each base station can only offer the highest data rates to users typically one or two kilometers away, so a truly vast number would be needed to cover all the railway routes in a country the size of the USA, or even France," Thornton says."