RADAR and Doppler RADAR: Invention and History

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Sir Robert Alexander Watson-Watt created the first radar system in 1935, but several other inventors have taken his original concept and have expounded and improved on it over the years. The question of who invented radar is a bit murky as a result. Many men had a hand in developing radar as we know it today. 

Sir Robert Alexander Watson-Watt 

Born in 1892 in Brechin, Angus, Scotland and educated at St. Andrews University, Watson-Watt was a physicist who worked at the British Meteorological Office. In 1917, he designed devices that could locate thunderstorms. Watson-Watt coined the phrase "ionosphere" in 1926. He was appointed as the director of radio research at the British National Physical Laboratory in 1935 where he completed his research to develop a radar system that could locate aircraft. Radar was officially awarded a British patent in April 1935.

Watson-Watt's other contributions include a cathode-ray direction finder that's used to study atmospheric phenomena, research in electromagnetic radiation, and inventions used for flight safety. He died in 1973.

Heinrich Hertz

In 1886, Germany physicist Heinrich Hertz discovered that an electric current in a conducting wire radiates electromagnetic waves into the surrounding space when swinging rapidly back and forth. Today, we call such a wire an antenna. Hertz went on to detect these oscillations in his lab using an electric spark in which the current oscillates rapidly. These radio waves were first known as "Hertzian waves.” Today we measure frequencies in Hertz (Hz) -- oscillations per second --and at radio frequencies in megahertz (MHz).

Hertz was the first to experimentally demonstrate the production and detection of “Maxwell’s waves,” a discovery that leads directly to radio. He died in 1894. 

James Clerk Maxwell

James Clark Maxwell was a Scottish physicist best known for combining the fields of electricity and magnetism to create the theory of the electromagnetic field. Born in 1831 to a wealthy family, the young Maxwell’s studies took him to the Edinburgh Academy where he published his first academic paper in the Proceedings of the Royal Society of Edinburgh at the astounding age of 14. He later attended the University of Edinburgh and the University of Cambridge.

Maxwell began his career as a professor by filling in the vacant Chair of Natural Philosophy at Aberdeen’s Marischal College in 1856. Then Aberdeen combined its two colleges into one university in 1860, leaving room for only one Natural Philosophy professorship which went to David Thomson. Maxwell went on to become Professor of Physics and Astronomy at King’s College in London, an appointment that would form the foundation of some of the most influential theory of his lifetime.

His paper on physical lines of force took two years to create and was ultimately published in several parts. The paper introduced his pivotal theory of electromagnetism – that electromagnetic waves travel at the speed of light and that light exists in the same medium as electric and magnetic phenomena. Maxwell’s 1873 publication of “A Treatise on Electricity and Magnetism” produced the fullest explanation of his four partial different equations which would go on to become a major influence on Albert Einstein’s theory of relativity. Einstein summed up the monumental achievement of Maxwell’s life's work with these words: “This change in the conception of reality is the most profound and the most fruitful that physics has experienced since the time of Newton.”

Considered one of the greatest scientific minds the world has ever known, Maxwell’s contributions extend beyond the realm of electromagnetic theory to include an acclaimed study of the dynamics of Saturn’s rings, the somewhat accidental -- although still important—capturing of the first color photograph, and his kinetic theory of gases which led to a law relating to the distribution of molecular velocities. He died on November 5, 1879, at the age of 48 from abdominal cancer.

Christian Andreas Doppler

Doppler radar gets its name from Christian Andreas Doppler, an Austrian physicist. Doppler first described how the observed frequency of light and sound waves was affected by the relative motion of the source and the detector in 1842. This phenomenon became known as the Doppler effect, most often demonstrated by the change in the sound wave of a passing train. The train's whistle becomes higher in pitch as it approaches and lower in pitch as it moves away.

Doppler determined that the number of sound waves reaching the ear in a given amount of time, called the frequency, determines the tone or pitch that’s heard. The tone remains the same as long as you’re not moving. As the train moves closer, the number of sound waves reaching your ear in a given amount of time increases and the pitch therefore increases. The opposite occurs as the train moves away from you.

Dr. Robert Rines

Robert Rines is the inventor of high definition radar and the sonogram. A patent attorney, Rines founded the Franklin Pierce Law Center and devoted a great deal of time to chasing the Loch Ness monster, a mission for which he's best known. He was a major supporter of inventors and a defender of inventors' rights. Rines died in 2009.

Luis Walter Alvarez

Luis Alvarez invented a radio distance and direction indicator, a landing system for aircrafts and a radar system for locating planes. He also co-invented the hydrogen bubble chamber which is used to detect subatomic particles. He developed the microwave beacon, the linear radar antennae, and ground-controlled radar landing approaches for aircraft. An American physicist, Alvarez won the 1968 Nobel Prize in physics for his studies. His many inventions demonstrate ingenious applications of physics to other scientific areas. He died in 1988.

John Logie Baird

John Logie Baird Baird patented various inventions related to radar and fiber optics, but he's best remembered as the inventor of mechanical television—one of the earliest versions of television. Along with American Clarence W. Hansell, Baird patented the idea of using arrays of transparent rods to transmit images for television and facsimiles in the 1920s. His 30-line images were the first demonstrations of television by reflected light rather than back-lit silhouettes.

The television pioneer created the first televised pictures of objects in motion in 1924, the first televised human face in 1925, and the first moving object image in 1926. His 1928 trans-Atlantic transmission of the image of a human face was a broadcasting milestone. Color television, stereoscopic television, and television by infra-red light were all demonstrated by Baird before 1930.

When he successfully lobbied for broadcast time with the British Broadcasting Company, the BBC began broadcasting television on the Baird 30-line system in 1929. The first British television play, "The Man with the Flower in his Mouth,” was transmitted in July 1930. The BBC adopted television service using the electronic television technology of Marconi-EMI—the world's first regular high-resolution service at 405 lines per picture – in 1936. This technology finally won out over Baird's system.

Baird died in 1946 in Bexhill-on-Sea, Sussex, England.

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Bellis, Mary. "RADAR and Doppler RADAR: Invention and History." ThoughtCo, Aug. 27, 2020, thoughtco.com/radar-and-doppler-history-4070020. Bellis, Mary. (2020, August 27). RADAR and Doppler RADAR: Invention and History. Retrieved from https://www.thoughtco.com/radar-and-doppler-history-4070020 Bellis, Mary. "RADAR and Doppler RADAR: Invention and History." ThoughtCo. https://www.thoughtco.com/radar-and-doppler-history-4070020 (accessed March 30, 2023).