Radar apparatus for the detection of radio echoes from aircraft, used by Robert Watson-Watt in February 1935, England, United Kingdom
This receiver, originally used at the UK National Physical Laboratory for measurements on the ionosphere, was employed by Robert Watson-Watt (1892-1973) in the first convincing demonstration of radar. The experiment took place in a field in Northamptonshire on 26 February 1935.
While a Heyford bomber flew to and fro at 1524 m (5000 ft) in the beam from the BBC Empire Short-Wave transmitter at nearby Daventry, Watson-Watt studied a flickering trace on a cathode-ray tube. Deflections of the trace when the bomber was 13 km (8 miles) away confirmed his belief that distant aircraft could be detected from their radio reflections.