The seminal Daventry Experiment of 1935 proved the basic concept of radar was feasible and led to the rapid formation of the Air Ministry Experimental Station (AMES) at Bawdsey Manor to develop them.

The AMES team's primary concern was the development and deployment of the Chain Home (CH) system, providing early warning for raids approaching the UK.

Bowen started development of a new system operating at shorter wavelengths, first at 6.7 m following work by the British Army, and then finally settling on 1.5 m, the practical limit of available technology.

[10] The Airborne Group had been experimenting with microwave systems as early as 1938 after discovering that a suitable arrangement of the RCA acorn tubes could be operated at wavelengths as low as 30 cm.

[12] Bowen and his counterpart at the Admiralty Signals Establishment (ASE), Canadian polymath Charles Wright, met at Bawdsey in the spring or summer of 1939 and considered the issue of a microwave aircraft interception radar.

Bowen agreed that the main problem with the range limits of the AI sets was the floodlight-like transmissions and that the easy way to fix this would be to narrow the beam, focussing the power into a smaller area.

[13] With both forces desiring a 10 cm system, Tizard visited the General Electric Company's (GEC) Hirst Research Centre in Wembley in November 1939 to discuss the issue.

This was a problematic device because the filaments warming the cathode tended to burn out continually, requiring the system to be disconnected from the water supply, unsealed, repaired, and then re-assembled.

The next day, Dee, Watt and Rowe were on hand, but with no convenient aircraft available the team instead demonstrated the system by detecting the returns from a tin sheet being held by Reg Batt bicycling across a nearby cliff.

GEC solved the problem of having the signal turned off half the time by using two dishes mounted back-to-back and switching the output of the magnetron to the one facing forward at that instant.

With the helical-scan system, the radar dish was moving horizontally, producing a series of stripes across the screen while scanning up and down so subsequent lines were above or below the last pass.

In the A-scope, a time base generator pulls the CRT beam across the screen horizontally, and blips indicate the range to the target along the line the radar is currently pointed.

The remaining cavity was fed a tiny amount of the output from the magnetron, causing the electrons passing by it to take up the pattern of the radio signal (this is the basis of all klystrons).

Lovell had attempted a solution using two dipoles in front of a common parabolic reflector, separated by a 5 inches (13 cm) metal disk, but found that enough signal leaked through to cause the crystal detectors in the receivers to burn out.

This final piece of the puzzle was provided by Arthur Cooke, who suggested using the Sutton tube filled with a dilute gas as a switch, replacing the spark gap system.

After several months of work, Hodgkin and Edwards managed to provide a tuning control that muted down the weaker signals, leaving a sharp ring indicating the aircraft altitude.

Watt was able to rapidly respond to this threat by taking over deliveries of a British Army radar originally developed to detect ships in the English Channel, mounting them on tall masts to provide a long horizon, and renaming them Chain Home Low (CHL).

Dowding was impressed, and before leaving to return to the UK, met with his counterpart, James E. Chaney, telling him about the system's performance and pressing for its immediate development for purchase by the RAF.

The reason why the two firms were involved was that senior people at the TRE, Dee, Skinner and Lewis, felt that GEC would always drag its feet because it hankered after its 20 cm project and that the only way to get things moving was to inject some competition into the system.

Luftflotte 3 assembled a fleet of 474 bombers, including the newer Junkers Ju 188s and Heinkel He 177 as well as additional numbers of the Messerschmitt Me 410 heavy fighter in the jabo role.

[l] Williams applied some of the techniques he had used on a differential analyser to produce a system known as the Velodyne that tracked smoothly in spite of hard manoeuvring and large crossing speeds by the target.

However, Western Electric had been concentrating on the SCR-520 for mounting in the Northrop P-61 Black Widow, the American 15-ton flight weight, 66 ft wingspan purpose-designed twin-engined night fighter large enough to carry it.

Small batches were completed on various marks of Mosquitos before the production was turned over entirely for installation on the NF.XIX, which featured Rolls-Royce Merlin 25 engines and a strengthened wing allowing them to carry external fuel tanks.

This led to an effort to greatly enhance the UK's radar systems under the ROTOR program, as well as introduce a new night fighter that was able to work well against the 350 miles per hour (560 km/h) speeds of the Tu-4.

The signal was transmitted from a small vertically oriented half-wave dipole antenna and reflector mounted at the end of a post passing through a hole in the middle of the dish.

For targets located far from the centreline, the radar would produce 4 or 5 individual blips as the scanner rotated, causing a short arc about 10 degrees wide to show on the display.

One was due to the fact that the dipole was slightly past the outer edge of the dish when it was tilted anywhere close to the centreline, allowing small amounts of the signal to travel directly to the ground and back.

This meant that in spite of the relatively wide beam, the arcs were quite sharp and even small angles would cause the signals to disappear at some point and create a gap in the return.

[115] Switching the system to beacon mode slowed the pulse repetition frequency to give the signals more time to travel, stretching the range to 100 miles (160 km).

Since water and land produced very different ground returns, using this mode was sometimes useful for finding coastlines, large objects and ships, which it could do at ranges as great as 40 to 50 miles (64–80 km).