Differences

This shows you the differences between two versions of the page.

--- radar:history [2018/06/10 21:49] – galkina
+++ radar:history [2026/04/28 15:13] (current) – external edit 127.0.0.1
@@ Line 225: / Line 225: @@
 Runge, now with Hans Hollmann as a consultant, continued in developing a 1.8 m (170 MHz) system using pulse-modulation. Wilhelm Stepp developed a transmit-receive device (a duplexer) for allowing a common antenna. Stepp also code-named the system Darmstadt after his home town, starting the practice in Telefunken of giving the systems names of cities. The system, with only a few watts transmitter power, was first tested in February 1936, detecting an aircraft at about 5 km (3.1 mi) distance. This led the Luftwaffe to fund the development of a 50 cm (600 MHz) gun-laying system, the [[https://en.wikipedia.org/wiki/W%C3%BCrzburg_radar|Würzburg]].
-{{https://upload.wikimedia.org/wikipedia/commons/3/3b/Bundesarchiv_Bild_101I-662-6660-27A%2C_Frankreich%2C_Radarger%C3%A4t_%22W%C3%BCrzburg%22.jpg}}
+{{https://upload.wikimedia.org/wikipedia/commons/3/3b/Bundesarchiv_Bild_101I-662-6660-27A%2C_Frankreich%2C_Radarger%C3%A4t_%22W%C3%BCrzburg%22.jpg?200}}
 Würzburg D in use. The quirl conical scanning antenna is prominent.
@@ Line 638: / Line 638: @@
 ==Bibliography==
   -https://en.wikipedia.org/wiki/History_of_radar
+----
+===France===
+In 1927, French physicists [[https://en.wikipedia.org/wiki/Camille_Gutton|Camille Gutton]] and Emile Pierret experimented with magnetrons and other devices generating wavelengths going down to 16 cm. Camille's son, Henri Gutton, was with the Compagnie générale de la télégraphie sans fil (CSF) where he and Robert Warneck improved his father's magnetrons.
+In 1934, following systematic studies on the magnetron, the research branch of the CSF, headed by Maurice Ponte, submitted a patent application for a device designed to detect obstacles using continuous radiation of ultra-short wavelengths produced by a magnetron.[57] These were still CW systems and depended on Doppler interference for detection. However, as most modern radars, antennas were collocated. The device was measuring distance and azimuth but not directly as in the later "radar" on a screen (1939). Still, this was the first patent of an operational radio-detection apparatus using centimetric wavelengths.
+The system was tested in late 1934 aboard the cargo ship Oregon, with two transmitters working at 80 cm and 16 cm wavelengths. Coastlines and boats were detected from a range of 10–12 nautical miles. The shortest wavelength was chosen for the final design, which equipped the liner SS Normandie as early as mid-1935 for operational use.
+In late 1937, Maurice Elie at SFR developed a means of pulse-modulating transmitter tubes. This led to a new 16-cm system with a peak power near 500 W and a pulse width of 6 μs. French and U.S. patents were filed in December 1939. The system was planned to be sea-tested aboard the Normandie, but this was cancelled at the outbreak of war.
+At the same time, Pierre David at the Laboratoire National de Radioélectricité (National Laboratory of Radioelectricity, LNR) experimented with reflected radio signals at about a meter wavelength. Starting in 1931, he observed that aircraft caused interference to the signals. The LNR then initiated research on a detection technique called barrage électromagnétique (electromagnetic curtain). While this could indicate the general location of penetration, precise determination of direction and speed was not possible.
+In 1936, the Défense Aérienne du Territoire (Defence of Air Territory), ran tests on David’s electromagnetic curtain. In the tests, the system detected most of the entering aircraft, but too many were missed. As the war grew closer, the need for an aircraft detection was critical. David realized the advantages of a pulsed system, and in October 1938 he designed a 50 MHz, pulse-modulated system with a peak-pulse power of 12 kW. This was built by the firm SADIR.
+France declared war on Germany on September 1, 1939, and there was a great need for an early-warning detection system. The SADIR system was taken to near Toulon, and detected and measured the range of invading aircraft as far as 55 km (34 mi). The SFR pulsed system was set up near Paris where it detected aircraft at ranges up to 130 km (81 mi). However, the German advance was overwhelming and emergency measures had to be taken; it was too late for France to develop radars alone and it was decided that her breakthroughs would be shared with her allies.
+==Bibliography==
+  -https://en.wikipedia.org/wiki/History_of_radar