SHORTLY after the UK’s Royal Navy started using radar, it found to its irritation that targets would sometimes disappear from screens thanks to a quirk of the sea air. Now the same phenomenon is being used in Australia to set up a data link allowing conditions on the Great Barrier Reef to be monitored remotely.
Evaporation ducting, as the phenomenon is called, allows radio signals to travel much further than usual. With regular line-of-sight transmission, the range of a ground-based transmitter is limited to 30 kilometres or so by the Earth’s curvature. Increasing the range requires taller transmitters, which is…
