Cave Radio – Talking Through Solid Rock

Photos and diagrams by Mike Bedford, except where otherwise stated. Featured photo by Bartek Biela.

This article appeared in Make: Vol. 96. Subscribe to Make: for the latest articles.

Radio signals don’t pass through rock to reach caves, mines, and tunnels, right? You’d be excused for thinking so, because you’ve surely lost your favorite radio station, or your phone conversation, when you’ve driven into a tunnel. But things aren’t that simple. By using special techniques, radio communication between the surface and underground really is possible, and you can try it for yourself.

Commercial equipment is available for communicating with miners, but these systems are massively expensive and not really portable. But cave explorers also need to talk to their colleagues on the surface — we’ll