Karl Küpfmüller

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Karl Küpfmüller (born October 6, 1897 in Nuremberg ; † December 26, 1977 in Darmstadt ) was a German electrical engineer and university professor in the fields of communications engineering , measurement and control technology, acoustics, information theory and theoretical electrical engineering.


Karl Küpfmüller was born in 1897 as the son of the chief locomotive driver Ernst Küpfmüller († 1914) and his wife Eva. Körbitz († 1919) born in Nuremberg. From 1903 to 1907 he attended primary school in Nuremberg and then until 1913 the secondary school. Küpfmüller studied electrical engineering at the Royal Bavarian Technical Center in Nuremberg from 1913 to 1919 (from 1932 Ohm Polytechnic ), interrupted by his military service with the infantry 1917-18. From 1919 to 1921 he was employed in the Telegraph Research Office of the Deutsche Post in Berlin, where he worked for Karl Willy Wagner . From 1921 to 1928 he worked as a senior engineer in the central laboratory of Siemens & Halske AG in Berlin. During this time he published numerous specialist articles and was full professor for general and theoretical electrical engineering at the Technical University of Danzig from 1928 to 1935 and at the TH Berlin from October 1, 1935 to March 31, 1937 . There he succeeded Ernst Orlich (1868–1935).

On September 1, 1933 he joined the NS motor corps. On May 1, 1934 he became a member of the SA (until 1937), from 1937 he was a member of the NSDAP and SS (where he rose to SS-Obersturmbannführer in 1944). In November 1933 he signed the professors' declaration of Adolf Hitler at German universities and colleges . From April 1, 1937 to 1941, Küpfmüller was head of communications technology development at Siemens-Wernerwerk for telecommunications technology and then until May 1945 director of the central development department at Siemens & Halske. From August 1942 Küpfmüller headed the communications commission of the Reich Ministry for Armaments and Ammunition. In June 1943 he was also appointed head of the radio measurement technology commission.

During this time he continued to function as an honorary professor at the TH Berlin and gave lectures on systems theory . In 1940 he was appointed to the Kaiser Wilhelm Institute for Materials Research, where he led a working group on torpedo control on behalf of the Navy to remedy the torpedo crisis . In January 1944 he was appointed head of the scientific command staff of the Navy. On April 30, 1945 he was awarded the Knight's Cross of the War Merit Cross with Swords.

Küpfmüller was briefly arrested by the British after the end of the Second World War and interrogated in England. Because of his high SS rank and his high positions in armaments research, he was captured by the Americans in autumn 1945 and brought to Dachau. In December 1946 he was transferred to the Hammelburg internment camp in Lower Franconia for former NSDAP members. Here he worked in an advisory capacity for Rohde & Schwarz . There he met Hermann Druckrey , which resulted in a scientific collaboration, which resulted in the Druckrey-Küpfmüller equation , among other things . Küpfmüller remained in Hammelburg until his denazification. At the intervention of Lothar Rohde , who also acted as a witness, the proceedings were accelerated. In the arbitration chamber proceedings before the arbitration chamber in Ansbach-Land, he was classified as a fellow traveler on November 4, 1947, largely based on his largely false information about his memberships and offices in the Nazi regime, and sentenced to an atonement of 3,040 Reichsmarks.

From July 1, 1948 to May 1952, he was a member of the board and head of development at Standard Elektrizitäts-Gesellschaft (later Standard Elektrik Lorenz AG) in Stuttgart. In May 1951 he also took on an honorary professorship at the TH Stuttgart .

Effective June 1, 1952, Küpfmüller was appointed full professor at the TH Darmstadt . Here he succeeded Hans Busch , who had an advisory role on the appointment committee and wanted Küpfmüller to be his successor. The chairman of the appointment committee was Friedrich-Wilhelm Gundlach , who knew Küpfmüller from his time in Berlin and from his time at the armaments company Funkstrahl GmbH in Constance. Until March 31, 1963, Karl Küpfmüller taught and researched at the Institute for General Telecommunications with a focus on communications engineering , control engineering , pattern recognition , speech synthesis and information theory in the electrical engineering and information technology department . 1955/56 Küpfmüller was rector of the TH Darmstadt. From 1955 to 1957 he was Vice President of the German Research Foundation and from 1955/56 also Chairman of the Association of German Electrical Engineers (VDE) .

As a professor for electrical engineering at the TH Darmstadt, Küpfmüller gave significant impetus to communications technology with his scientific work. He founded the system theory of electrical communications and thus contributed significantly to the development of long-distance telephony. In 1924 he established a relationship between the bandwidth and the settling time of signals, which later became known under the name Küpfmüller's uncertainty relation and, in quantum mechanics, has the better-known Heisenberg uncertainty relation as an analogue .

In 1968, he received the Werner-von-Siemens-Ring and numerous other awards for his contributions to communications technology and system theory .

Küpfmüller died of heart and kidney failure at the age of 80. He was buried in the Darmstadt forest cemetery. He was married to Elisabeth Riedel for the first time from 1921 to 1940. Since 1941 he was in his second marriage with his secretary Eva geb. Luckan (* 1911), daughter of an evangelical pastor, married. The marriages were childless. He left a stepdaughter named Doris (1934-1998).


  • 1932: Gauß Weber commemorative coin.
  • 1943: War Merit Cross 1st Class without swords
  • 1944: Dr. Fritz Todt Prize in gold
  • 1944: Dr.-Ing. E. h. University of Gdansk.
  • April 30, 1945: Knight's Cross of the War Merit Cross with Swords
  • 1952: Philipp Reis badge
  • 1954: Full member of the Mainz Academy of Sciences.
  • 1959: Golden Cedergren Medal.
  • 1962: VDE ring of honor
  • 1963: Culture Prize of the City of Nuremberg.
  • 1964: Honorary membership of the VDE
  • 1969: Honorary President of the German Society for Cybernetics.
  • 1968: Werner-von-Siemens-Ring .
  • 1976: Dr.-Ing. E. h. University of Erlangen.
  • 1976: DIN badge of honor
  • 1977: Johann Heinrich Merck award from the city of Darmstadt.

Awards named after Küpfmüller

  • Karl-Küpfmüller-Ring of the TU Darmstadt
    This award was donated in October 1977 on the occasion of Karl Küpfmüller's 80th birthday as part of the 100th anniversary of the TH Darmstadt. According to the statutes, the Karl-Küpfmüller-Ring should "be awarded as an extraordinary honor to scientists who, through their research, have promoted scientific knowledge outside of their specialist field and have significantly influenced scientific or technical development" . The previous winners of the Karl-Küpfmüller-Ring are:


  • Introduction to theoretical electrical engineering. 18th edition, Springer, Berlin 2008, ISBN 978-3-540-78589-7 .
  • The system theory of electrical communications. Hirzel, Stuttgart.
  • Low current technology. In: Handbuch der Experimentalphysik. Academic Publishing Company, Leipzig 1931/1932.
  • Technology and math. In: Technical University of Darmstadt. Technical University of Darmstadt, Rector's speech on November 29, 1952.
  • Message and energy. In: Technical University of Darmstadt. Technical University of Darmstadt, Rector's speech on December 2, 1955.
  • About the dynamics of the automatic gain control. In: Electrical communications engineering. Volume 5, No. 11, pp. 459-467, 1928. Early work with foundations for sampling theory ( Nyquist-Shannon sampling theorem ). Independent and at the same time as Nyquist.


  • Ralph Erskine: Radio direction finding as an allied weapon against German submarines 1939 - 1945. (also online: radio direction finding - PDF; 340 kB).
  • Michael Grüttner : Biographical Lexicon on National Socialist Science Policy, Heidelberg, 2004, p. 102 f.
  • Helmut Mielert:  Küpfmüller, Karl. In: New German Biography (NDB). Volume 13, Duncker & Humblot, Berlin 1982, ISBN 3-428-00194-X , p. 230 ( digitized version ).
  • Joachim Hagenauer / Martin Pabst: Adaptation, insubordination and resistance. Karl Küpfmüller, Hans Piloty , Hans Ferdinand Mayer - Three scientists of communications technology in the "Third Reich", Munich 2014, ISBN 978-3-7696-2565-3 (also online - PDF; 2.025 kB).
  • Karl-Heinz Ludwig: Technology and Engineers in the Third Reich, Düsseldorf 1979, p. 259 ff.
  • Hans Sckommodau: Obituaries for Erhard Lommatzsch, Walter Artelt, Herbert O'Daniel, Franz Beyerle, Franz Böhm, Karl Küpfmüller, Gerhard Kleiner, Ernst Langlotz, Paul Royen. (= Meeting reports of the Scientific Society at the Johann Wolfgang Goethe University Frankfurt am Main; 17.2) Steiner, Wiesbaden 1980, ISBN 3-515-03392-0 .

Web links

Individual evidence

  1. a b Helmut Maier : Research as a weapon. Armaments research in the Kaiser Wilhelm Society and the Kaiser Wilhelm Institute for Metal Research 1900-1945 / 48 . Wallstein Verlag, Göttingen 2007, ISBN 978-3-8353-0109-2 , p. 710 in the Google book search.
  2. Confession, p. 132
  3. Helmut Maier: Armaments research in National Socialism. History of the Kaiser Wilhelm Society in National Socialism , Volume 3. Wallstein Verlag, Göttingen 2002, ISBN 978-3-89244-497-8 , p. 98 in the Google book search.
  4. ZPF no. 23/1953; P. 877