Tesla-style through-ground magnetic wave communicator

Interesting article over at AAAS’s ScienceNOW about MagneLink, a short-range wireless communications system being developed by Lockheed-Martin that uses magnetic fields, rather than radio waves, to transmit information. Supposedly Tesla first experimented with such a system, hoping to compete with radio, in the 1890s. For most wireless applications, radio is clearly a superior system; magnetic wave communicators suffer from limited range and poor signal-to-noise ratios. There’s one thing they can do, however, that radio can’t: easily transmit through hundreds of meters of rock or clay. They can, therefore, be depended on in the event of a mining accident to allow trapped workers to communicate with rescue personnel in situations where radio is impossible and wired systems may be inoperable or inaccessible.

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