Origin of radio direction finding and radar technology

Born 13 April 1892
Brechin, Angus, Scotland, UK
Died 5 December 1973 (aged 81)
Inverness, Scotland, UK

Sir Robert Alexander Watson-Watt, a descendant of James Watt¹, the famous engineer and inventor of the practical steam engine, was a British pioneer of radio direction finding and radar technology.

James Watt (1736-1819)

Robert Watson-Watt spend his young ages in the familial environnement of the city of Durness. His mother, Annag Watt an important member of the local community, raised her alone after the death of his father, Shaw Watson, in 1896.

Annag Watt and Shaw Watson (1895)

Robert start to study radio, or “wireless telegraphy” after been graduated with a BSc in engineering in 1912. In 1916 Watson-Watt wanted a job with the War Office, but nothing obvious was available in communications. Instead he joined the Meteorological Office, which was interested in his ideas on the use of radio for the detection of thunderstorms². Lightning gives off a radio signal as it ionizes the air, and his goal was to detect this signal to warn pilots of approaching thunderstorms.  In his first experimentation, looking for the specific material to set up kite antenna, Robert remember this blanket that is mother was using and which had this physical reaction when thunderstorms was close. Starting his research about this blanket, Robert discover that the central pattern was made with a special kind of wool. After looking why this material has this reaction, Robert Watson-Watt realised that this wool has specific proprieties like conducting electricity. He also find that this specific shape act as an antenna, which is explained the capacity to feel radio signal from ionisation.

Pattern of the blanket

His early experiments, using the blanket on the surface of the kit, were successful in detecting the signal and he quickly proved to be able to do so at ranges up to 2,500 km. Location was determined by rotating the wool antenna to maximise (or minimise) the signal, thus “pointing” to the storm.

First prototype of kite antenna

In 1935 Watt and his assistant Arnold Frederic Wilkins suggested to Harry Wimperis, Director of Scientific Research at the Air Ministry to use radio signals to locate aircraft at long distances. Watt led the development of a practical device, which entered service in 1938 under the code name Chain Home. This system provided the vital advance information that helped the Royal Air Force win the Battle of Britain.

Map of the Chain Home

In July 1938, Watson-Watt left Bawdsey Manor and took up the post of Director of Communications Development (DCD-RAE). In 1939, Sir George Lee took over the job of DCD, and Watson-Watt became Scientific Advisor on Telecommunications (SAT) to the Ministry of Aircraft Production, travelling to the US in 1941 to advise them on the severe inadequacies of their air defence, illustrated by the Pearl Harbor attack. He was knighted by George VI in 1942 and received the US Medal for Merit in 1946.

¹ James Watt,The Godfather of the Industrial Revolution, he made us an offer that we couldn’t refuse; an efficient way of travelling, oh and you know, putting Scotland on the right (train) tracks of the industrial revolution. One day, Watt was working on a Newcomen engine and noted how inefficient it was. He discovered that if he could use a separate chamber to condense steam without cooling the rest of the engine, it would run efficiently and that’s pretty much what he did. By making this discovery, not only did rail travel change but the new steam engine replaced the water wheel as the main sources of power for British industry also.
² The first Lightning detection device was invented in 1894 by Alexander Stepanovich Popov. It also was the first radio receiver in the world.

How it’s work?