48 Fun Facts About Radar

What does the acronym RADAR stand for?

RADAR stands for radio detection and ranging, a term coined in 1940; it has since become an ordinary lowercase noun.

Which organisation coined the term RADAR in 1940?

The US Navy coined RADAR in 1940 as a cover term; Britain had been calling the same technology RDF, for radio direction finding.

Which German physicist showed in 1886 that radio waves reflect off solid objects?

Heinrich Hertz, who first proved the electromagnetic waves Maxwell predicted, showed in his 1886-88 experiments that radio waves reflect from metal surfaces.

Which German inventor patented the 'telemobiloscope' in 1904 to detect ships in fog?

Christian Hülsmeyer patented his telemobiloscope in 1904; it rang a bell when a ship came within range but could not measure distance, and the German navy declined it.

Which Russian physicist noted in 1897 that a passing ship disturbed radio signals?

Alexander Popov, testing ship-to-ship radio in 1897, noted that a passing vessel disturbed the signal and remarked it might detect objects, but took it no further.

Which Scottish engineer led the British team that demonstrated pulsed radar in 1935?

Robert Watson-Watt, who had earlier used radio to locate thunderstorms for airmen, led the team whose pulsed radar tracked aircraft from Orfordness in 1935.

What rumoured German weapon prompted the enquiry that led Britain to radar?

Arnold Wilkins showed the death ray was impossible but suggested radio detection instead.

Whose shortwave transmitter was borrowed for the Daventry Experiment of 26 February 1935?

The BBC's Empire shortwave transmitter at Daventry supplied the signal; a Handley Page Heyford bomber flew through its beam while Wilkins's receiver in a nearby field picked up echoes.

What did Watson-Watt reportedly exclaim after the Daventry test succeeded?

Watson-Watt is reported to have said 'Britain has become an island again!' after the Daventry echoes; £12,300 of funding followed within days.

What was the codename of Britain's ring of coastal early-warning radar stations?

Chain Home, officially the AMES Type 1, was the world's first early-warning radar network, built by the RAF before and during the Second World War.

Where in Suffolk did Watson-Watt's team develop the coastal radar stations from 1936?

Bawdsey Manor, bought by the Air Ministry in 1936, became the Bawdsey Research Station; by 1940 its coastal stations ringed the whole UK coast including Northern Ireland.

Which 1940 air campaign did the coastal radar chain's early warning help the RAF to win?

Radar early warning let Fighter Command win the 1940 Battle of Britain by scrambling squadrons only when raids approached, the core of the 'Dowding system'.

Which two Birmingham physicists built the improved cavity magnetron in 1940?

John Randall and Harry Boot at the University of Birmingham ran their cavity magnetron on 21 February 1940; it gave about 400 watts at a 9.8 cm wavelength, unprecedented at the time.

What everyday appliance later used the cavity magnetron?

The microwave oven runs on a cavity magnetron; a 1.1-kilowatt oven input yields about 700 watts of microwaves, around 65% efficiency.

Which 1940 British delegation carried a magnetron to the United States?

The Tizard Mission of September 1940 carried a cavity magnetron to Washington; historian James Phinney Baxter called it 'the most valuable cargo ever brought to our shores'.

Which secret US lab, organised by Alfred Loomis, developed microwave radar from 1941 to 1945?

The MIT Radiation Laboratory opened in Cambridge, Massachusetts in October 1940 after Loomis's Microwave Committee saw the British magnetron; by 1945 it employed nearly 4,000 people and had produced the SCR-584 gun-laying radar.

Where on Oahu did an SCR-270 radar spot the incoming Japanese planes in 1941?

The SCR-270 at Opana Point on Oahu's north shore picked up the raid at 7:02 am; Lieutenant Kermit Tyler assumed the blip was six B-17s due from California.

Which American demonstrated the first elementary pulsed radar in December 1934?

Robert M. Page of the Naval Research Laboratory transmitted the first pulsed radar signals in December 1934, detecting a small aircraft about a mile away over the Potomac.

Which German firm demonstrated a pulsed radar system in May 1935?

GEMA, the firm set up to build Rudolf Kühnhold's sets, tested pulsed radar on the Baltic coast at Pelzerhaken in May 1935, weeks before Watson-Watt's Orfordness trials in June.

What did the Soviets call their first mass-produced radar, of which only 607 were built?

RUS-2 Redut, a metre-wave early-warning set, was the first Soviet radar built in quantity; work had slowed after pioneer P. K. Oshchepkov was sent to the gulag in 1937.

Which ocean liner had parts of a French obstacle-detecting radio set installed in 1935?

CSF fitted a 16 cm continuous-wave 'obstacle detector' built under Maurice Ponte to the liner Normandie in 1935; without pulses it sensed presence but not range.

What was the British codename for chaff, the strips of foil dropped to blind radar?

Britain called chaff 'Window'; the Germans called it Düppel, and both sides held it back for months for fear the other would copy it.

Over which city was the foil countermeasure first used, during Operation Gomorrah in 1943?

Window was first dropped over Hamburg on the night of 24-25 July 1943; German searchlights and flak radars wandered helplessly among the false echoes.

Chaff strips are cut to what fraction of the target radar's wavelength?

Chaff is cut to half the radar's wavelength, so each strip acts as a resonant dipole that re-radiates the signal strongly.

Which German radar was seized and brought to Britain in Operation Biting in 1942?

The Bruneval raid of February 1942 carried off key parts of a Würzburg set; examining its receiver and transmitter showed British scientists how it could be jammed.

What phenomenon lets radar read a target's speed from a change in the returned frequency?

Doppler weather radars can track wind and rotation inside storms.

Who invented the radar speed gun, working for the Automatic Signal Company in Connecticut?

John L. Barker Sr. and Ben Midlock, who had built radar for the military in the Second World War, devised the radar speed gun at Automatic Signal Company in Norwalk, Connecticut.

Which nearby body was first detected by radar in 1946?

Project Diana bounced radar off the Moon on 10 January 1946 from Fort Monmouth, New Jersey; later lunar radar mapped shadowed regions near its poles.

Which lab made the first unambiguous radar contact with Venus, on 10 March 1961?

The Jet Propulsion Laboratory's Goldstone antenna received Venus echoes on 10 March 1961; their timing gave a new, precise value for the astronomical unit.

How large was the Arecibo radar-radio dish that collapsed in 2020?

305 m (1,000 ft) across, the dish was completed in 1963 with a cable-mounted receiver and radar transmitters hanging 150 m above it.

Whose 1962 Soviet paper on edge waves shaped the design of American stealth aircraft?

Pyotr Ufimtsev's 1962 paper on the physical theory of diffraction was translated by the USAF in 1971; Lockheed's Skunk Works used its equations in the Have Blue bid.

Which aircraft made the word 'stealth' popular in the late 1980s?

The Lockheed F-117 Nighthawk, shown publicly in November 1988, made 'stealth' a household word; its first large-scale combat use came in the 1991 Gulf War.

What is the measure of how strongly an object scatters radio waves back called?

Radar cross-section measures how strongly a target scatters energy back toward the radar; a stealth aircraft's is a tiny fraction of a conventional jet's.

Returned radar power falls off with what power of the range in the radar equation?

Returned power falls with the fourth power of range: the signal spreads as 1/R² on the way out and the echo spreads as 1/R² again on the way back.

The Soviet Duga over-the-horizon radar was nicknamed what by shortwave listeners?

Shortwave listeners called Duga the 'Russian Woodpecker' for its 10 Hz tapping, which disrupted broadcasts worldwide; one array stands near Chernobyl.

Modern high-power radar transmitters replaced magnetrons in the 1960s with which devices?

Klystrons and travelling-wave tubes amplify a stable reference signal coherently, which the magnetron's pulse-to-pulse jumps in frequency and phase could not, so they suit Doppler processing and phased arrays.

Where did the radar band letters such as X, S and L originate?

The IEEE and ITU later adopted the letters, and they remain in military and aviation use.

On which company's aircraft was the first commercial radar device fitted in 1938?

A Bell Labs radio altimeter, the first commercial radar device, was fitted to United Air Lines aircraft in 1938; Bell's Lloyd Espenschied had conceived the idea in the 1920s.

A radar altimeter measures an aircraft's height above what?

The terrain directly beneath it is what a radar altimeter measures against, by timing a radio beam's trip to the ground and back; a barometric altimeter instead gives height above a datum such as sea level.

What Oklahoma event of May 1973 did a Doppler radar document in full for the first time?

A tornado that devastated Union City, just west of Oklahoma City, was tracked through its whole life cycle by the NSSL's Doppler radar.

What colour on a weather radar image usually marks the strongest returns?

Red or magenta marks the very strong returns, while weak ones show as blue or green.

Ground-penetrating radar uses which part of the radio spectrum?

It can image pipes, cables, rock, ice and even archaeological remains beneath the surface.

What is the rotating map-like radar display that paints echoes as blips called?

The plan position indicator (PPI) shows echoes as blips on a circular map-like screen as its trace sweeps round with the antenna; it is the classic radar display seen in films.

Which laser-based cousin of radar is often used by self-driving cars?

Lidar uses mostly infrared light from lasers rather than radio waves to measure range.

Which US Navy pair found in 1922 that ships crossing a Potomac radio beam made the signal fade?

A. Hoyt Taylor and Leo C. Young noticed in 1922 that a ship crossing their Potomac radio link faded the signal; the Navy did not follow up until Lawrence Hyland saw aircraft do the same in 1930.

How much did the UK government award Watson-Watt for radar, ten years after his knighthood?

The UK government awarded Watson-Watt £50,000 in 1952, ten years after his 1942 knighthood; he later moved to Canada and the United States and appeared on the TV show To Tell the Truth.

In which two cities did Christian Hülsmeyer demonstrate his ship-detecting telemobiloscope in 1904?

Hülsmeyer showed his telemobiloscope from a Rhine bridge in Cologne in May 1904 and at Rotterdam harbour that June, ringing a bell when a ship approached; the German navy showed no interest.

Which wartime navigation system, complementary to radar, was used by the RAF's Pathfinder force?

Oboe was the navigation system used by the RAF's Pathfinder force alongside radar; the war also drove demand for small, light sets to fit night fighters and maritime patrol aircraft.