Radar is a machine that uses radio waves for echolocation to detect objects such as aircraft, spacecraft, ships, guided missiles, motor vehicles, weather formations, and terrain.
The direction of an object is ascertained by transmitting a beam of short-wavelength short-pulse radio waves, and picking up the reflected beam. Distance is determined by timing the journey of the radio waves (traveling at the speed of light) to the object and back again.
In 1886, German physicist Heinrich Hertz was the first to show that radio waves could be reflected from solid objects.
A young German engineer named Christian Hülsmeyer was the first to use radio waves to detect the presence of distant objects. He obtained a British patent on September 23, 1904 for his apparatus which he called a Telemobiloscope. Hülsmeyer's Telemobiloscope was a spark-gap transmitter connected to an array of dipole antennas, and a coherer receiver with a cylindrical parabolic antenna that could rotate 360 degrees. When a reflected signal reached the receiver, a relay was actuated and, in turn, rang an electric bell.
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| Long-range radar antenna, used to track space objects and ballistic missiles. |
The direction of an object is ascertained by transmitting a beam of short-wavelength short-pulse radio waves, and picking up the reflected beam. Distance is determined by timing the journey of the radio waves (traveling at the speed of light) to the object and back again.
In 1886, German physicist Heinrich Hertz was the first to show that radio waves could be reflected from solid objects.
A young German engineer named Christian Hülsmeyer was the first to use radio waves to detect the presence of distant objects. He obtained a British patent on September 23, 1904 for his apparatus which he called a Telemobiloscope. Hülsmeyer's Telemobiloscope was a spark-gap transmitter connected to an array of dipole antennas, and a coherer receiver with a cylindrical parabolic antenna that could rotate 360 degrees. When a reflected signal reached the receiver, a relay was actuated and, in turn, rang an electric bell.
Hülsmeyer's invention was primarily designed as an anti-collision device for ships, and it worked well. He is often credited with the invention of radar, but his "Telemobiloscope," could not directly measure distance to a target and thus does not merit this full distinction.
The method of using radar to pinpoint small targets was developed independently in Britain, France, Germany, and the US in the 1930s.
Scottish engineer and inventor Robert Watson-Watt carried out a demonstration near Daventry which led directly to the development of RADAR in the United Kingdom on February 26, 1935. Having proved radar detection technology could work Watson-Watt received a patent for his system, on September 1, 1936.
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| The first workable unit built by Robert Watson-Watt and his team |
The Type 79 radar was the first radar system deployed by the Royal Navy. The first version of this radar, Type 79X, was mounted on the RN Signal School's tender, the minesweeper HMS Saltburn, in October 1936.
The British Army's first radar system, the Gun Laying radar, used up the nation's entire stockpile of chicken wire.
Radar was first put to practical use for aircraft detection by the British, who had a complete coastal chain of radar sets installed in time for the outbreak of World War II in 1939. This system provided the vital advance information that helped the Royal Air Force win the Battle of Britain when the ability to spot incoming German aircraft did away with the need to fly standing patrols.
During World War II, the German army used a radar system called Wotan. The British scientist R.V. Jones figured out how the system worked by assuming that it used a single beam based on the fact that the Germanic god Wotan had only one eye.
The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. This acronym of American origin replaced the previously used British abbreviation RDF (Radio Direction Finding). The term has since entered the English language as a standard word, radar, losing the capitalization in the process.
The Northamptonshire-born mathematician Dame Mary Cartwright (1900-1998) was the first woman to serve on the Royal Society council and as president of the London Mathematical Society. Her work was critical in perfecting radar equipment, saving countless lives in World War II. She hated praise and once wrote to scold a scientist for crediting her with more than she deserved.
During World War II, as a RAF officer, the science fiction writer Arthur C Clarke was in charge of the first radar talk-down equipment, the Ground Controlled Approach, during its experimental trials.
On February 15, 1954 Canada and the United States agreed to construct the Distant Early Warning Line, a system of radar stations in the far northern Arctic regions of Canada and Alaska.
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| POW-2, now Oliktok Long Range Radar Site |
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