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Radar Development in Germany
Aircraft Instrument Landing System (ILS)

Aircraft Warning  |  Ship Board  |  PPI | Airborne Telegraphy |  ILS
 

As early as 1929, Dr.Kramer and Dieckmann had invented the first aircraft ILS system. The system was demonstrated in 1932. In 1935, this ILS system was described in Prof. Dr. H.E. Hollmann's book "Physics and Technique of Ultrashort Waves" from which the picture below is taken. By 1935, both the Lorenz Co. and the Telefunken Co. were in full swing producing ILS and installing them at airports around the world. In Germany, under the sponsorship of Lufthansa, ILS  were installed at Breslau, Königsberg, Munich, Nurenberg and Stettin. By 1938, the Germany companies had also delivered and installed ILS at airports in Kastrup-Dänemark, Malmö-Sweden, Wilna and Warsaw-Polen, Prag-Tschesolavakia, Budapest-Hungary and Sidney and Melbourne-Australia. This system was also installed in England with the name "Standard Beam Approach."
The X-Beam and Y-Beam Systems were also used for navigation. In 1939-1940 during the "Battle of Britain", German bombers used radio beams operating at 33.3 MHz and later at 71 MHz. The system had the code name "Knickebein" during WWII and navigation was possible up to 350 km.
Below is a brief description of how ILS works. 

Deutsche Versuchsanstalt fuer Luftfahrt (DVL) developed a procedure built by the Lorenz Company for landings in bad visibility. A pulsed A-N signal of a VHF transmitter was received during approach and was switched in such a way that an A or N signal indicated a deviation from the selected approach path. This signal turned into a continuous sound when the airplane was on the approach path. A needle moving either to the right or left of an instrument panel served as visual indicator. VHF radar beacons set up in the direction of the approach and pointing vertically upward (outer marker beacons) marked the distance to the point of touchdown.
ILS information courtesy of  Dr. Peter Aichner.

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