Radar is now essential safety equipment for ships and planes, but it was planned as a deadly weapon.
Bouncing Waves. Radar uses radio waves to detect objects and can plot their position, course and speed. Various inventors helped develop it. German physicist Heinrich Hertz discovered radio waves in 1888 and found that they could bounce off other objects.
In 1904 Christian Hulsmeyer invented a way of detecting ships using radio waves, although his `telimobiloscope’ couldn’t measure distance.
Rudolf Kuhnold demonstrated the first practical radio detection equipment in Germany in 1934.
In 1935 the British government asked physicist Robert Watson-Watt to research radio waves and their use in destroying enemy planes. Watson-Watt quickly concluded that radio waves couldn’t be used as death-ray weapons but discovered that by bouncing radio waves off planes and measuring the delay in the echo, the direction and distance of the plane could be calculated. Only a few weeks after he’d begun his research, Watson-Watt demonstrated radar by plotting the course of an aircraft.
Radar was developed independently in Germany and the USA and was used extensively in the Second World War to plot enemy ships and planes. A US Navy Commander came up with the name, RAdio Detection And Ranging.
Magnetrons: The radio waves used in radar are generated by magnetrons, invented by John Randall and Henry Boot. Wartime radar operators discovered that magnetrons could be used as water heaters for their tea. Today they are used in microwave ovens.