Radar uses radio waves to enable aircraft, ships and ground stations to see far into their surroundings even at night and in bad weather. The metal antennas behind those waves also strongly reflect radar, making them highly visible to others-a deadly disadvantage during wartime. A new class of nonmetallic radio antennas can become invisible to radar-by ceasing to reflect radio waves-when deactivated. This innovation, called plasma antenna technology, is based on energizing gases in sealed tubes to form clouds of freely moving electrons and charged ions.
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