Hans Hollmann
Encyclopedia
Hans Erich Hollmann (4 November 1899 — 19 November 1960) was a German electronic specialist who made several breakthroughs in the development of radar
History of radar
The history of radar starts with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell's seminal work on electromagnetism...

.

Hollmann was born in Solingen
Solingen
Solingen is a city in North Rhine-Westphalia, Germany. It is located on the northern edge of the region called Bergisches Land, south of the Ruhr area, and with a 2009 population of 161,366 is the second largest city in the Bergisches Land...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

. He became interested in radio and even as a teenager subscribed to the technical magazines of the day. Late in World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 he became a prisoner of war of the French and did not return to Germany until 1920. He then studied at the Technical University at Darmstadt
Darmstadt
Darmstadt is a city in the Bundesland of Hesse in Germany, located in the southern part of the Rhine Main Area.The sandy soils in the Darmstadt area, ill-suited for agriculture in times before industrial fertilisation, prevented any larger settlement from developing, until the city became the seat...

 until he gained his doctorate in 1928.

Hollmann developed and built the first ultra short wave transmitter and receiver for centimeter and decimeter waves in 1927. This led to the development of the first microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

 telecommunication system.

In 1930 Hollmann moved to the Heinrich-Hertz Institute for Oscillatory Research in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

. As well as studying microwaves and cathode ray
Cathode ray
Cathode rays are streams of electrons observed in vacuum tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, the glass opposite of the negative electrode is observed to glow, due to electrons emitted from and travelling perpendicular to the cathode Cathode...

 tubes he also worked on the ionosphere research and on radio astronomy. In 1933 Hollmann became a lecturer at the Technical University in Berlin. He also became a consultant of Telefunken
Telefunken
Telefunken is a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the Allgemeine Elektricitäts-Gesellschaft...

.

In 1928 Hollmann, Hans-Karl von Willisen and Paul-Günther Erbslöh started a company called Gesellschaft für Elektroakustische und Mechanische Apparate (GEMA). This firm built the first radar in the autumn of 1934 for naval use. It used a 50cm wave-length and could find ships up to 10 km away. By 1935, they had developed the technology into two applications. For naval use, the Seetakt
Seetakt radar
The shipborne Seetakt radar was developed in the 1930s and was used by the German Navy during World War II.In Germany during the late 1920s, Hans Hollmann began working in the field of microwaves, which were to later become the basis of almost all radar systems. In 1935 he published Physics and...

system used a wavelength of 80 cm. A land based version at 120 cm wavelength was also developed as Freya
Freya radar
Freya was an early warning radar deployed by Germany during World War II, named after the Norse Goddess Freyja. During the war over a thousand stations were built. A naval version operating on a slightly different wavelength was also developed as Seetakt...

.

Telefunken set up a radar business in 1933 based on Hollmann's work and developed a much shorter-range gun-laying system called Würzburg
Würzburg radar
The Würzburg radar was the primary ground-based gun laying radar for both the Luftwaffe and the German Army during World War II. Initial development took place before the war, entering service in 1940. Eventually over 4,000 Würzburgs of various models were produced...

. During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, Freya and Würzburg worked in pairs. Freya would spot the incoming aircraft while the Würzburg calculated the distance and height.

In 1935, Hollmann wrote two books on microwaves, Physics and Technique of Ultrashort Waves and Seeing with Electromagnetic Waves, which were the inspiration for the development of centimetric radar in other countries despite some censorship
Censorship
thumb|[[Book burning]] following the [[1973 Chilean coup d'état|1973 coup]] that installed the [[Military government of Chile |Pinochet regime]] in Chile...

 of their contents.

During the war he supervised many research institutes in occupied countries and saved many scientists from being deported to Germany. His home and his laboratory in Berlin were destroyed during the war. After the war he was not allowed to work on microwaves but he turned his attention to a wide range of other fields in electronics. He eventually accepted an offer from the US Government to work in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

.

He was married to Gisela Schimmelbusch and had three children. He died in Los Angeles
Los Ángeles
Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...

in 1960.

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