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Prof. Dr. Hans E. Hollmann, the physicist
and "Father of Modern Radar"
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Translation of an article published in the December, 1959, issue of "Hochfrequenztechnik und Electroakustik",
by Professor H. Fruehauf, Chief Editor. 

On the fourth of November, 1959, Dr. Engineer Dr. h. c. (honorary) H. E. Hollmann celebrated his sixtieth birthday anniversary. We and many other of his colleagues and friends congratulate and wish him, who is now living far from his native country, good health and success for the future. Hollmann's pioneer work in many fields, especially in the fields of UHF and microwaves, as well as his approach to the field of "Electronics", justify the appreciation of his merits and his person. At the same time, a review of the past recalls many interesting details. Hollmann was born in 1899, the son of a medical doctor, P. Hollmann, in Solingen, Germany. Even while very young he showed great interest in the field to which he later dedicated himself. At the age of 12 he already had his own laboratory equipped with self-made instruments and devices. Soon he became interested in the field of radio and the like. He built his own X-ray machine and a great number of radio and high-frequency apparatus. When attending the high school of his native town, he was already a subscriber to the famous German periodical, "Annual Review of Wireless Telegraphy and Telephony", our present "Magazine for High-Frequency Technique and Electroacoustics". Later, he became a member of the editor's board and has worked with our magazine up through the present time. At the last days of World War I he was taken prisoner of war and was not returned from French captivity until the beginning of 1920.In his native country he began studying electrical engineering at the Technical University of Darmstadt where he did research work in acoustics. With the first Reverberation Oscillograms ever recorded, he won the first prize in a contest of the University. Very soon he dedicated himself to the field which had captured his interest from his early youth and was to become the most important part of his future work, namely, microwave and UHF. His UHF transmitters and receivers, built in the Institute of Physics in Darmstadt, created great interest. In 1927 he was able to generate, by means of feedback, a wave length below one meter, far ahead of all his competitors. In 1928 Hollmann graduated with a fundamental thesis on "The Mechanism of Barkhausen's Electron Oscillations". During the period of general economic collapse in Germany, he was granted a scholarship. He built the first telemetry system with frequency modulation, and since he had no official license, the tests were conducted with the radio waves propagating along a high-tension line. About the same time, he built a wire magnetophone with closed loop wire with two playback heads and continuous erasure. This device splits the signals of a broadcast station into two channels with a time delay and so produces a pseudostereophonic effect similar to present stereophonic methods. Later, he added a multiplicity of playback heads to these devices and produced an artificial reverberation which is now used by many broadcasting stations. At the beginning of 1930 Hollmann moved into the famous "Heinrich-Hertz Institute for Oscillatory Research" in Berlin. Under the direction of the President, Professor K. W. Wagner, he dedicated himself, not only to his favorite field the microwaves but also to electroacoustics, oscillography, and to preparations for the German expedition to the International Polar Year 1932-33. During this period he built an interesting device for measuring the Heaviside layer, and published several articles concerning ionosphere research and radio astronomy. In 1932 Hollmann discovered the dynamic transit time effect of first and second order in cathode-ray tubes. He also developed a phase compensated deflection system and laid the fundamentals of his later "Transit Time Oscillography". After the Lorenz Company had developed the first models of an efficient positive grid triode for him, Telefunken produced a high power grid triode (RS296) in a hard-glass envelope and with a high-power tungsten grid. In 1933 Hollmann graduated as a lecturer at the Technical University of Berlin with a thesis presented to the Prussian Academy of Science entitled "The Ultradynamic Excitation of Oscillations by Virtue of Feedback". Dr. Hollmann's intermediate-frequency modulation transmitters and receivers with directional antennas were shown at a radio exhibition in Berlin in 1932 and were used later to test and measure wave propagation across the Lake Wan near Berlin. A microwave department was established at the Telefunken Company, after a demonstration of his microwave link. These devices created by Dr. Hollmann overcame the competition of spark oscillators and infra-red transmitters which were considered very important at that time. As a result of his significant work, he became a consultant of the Telefunken Company, and many Telefunken patents have his name as inventor. 

The years between 1933 and 1936 covered two major phases of Hollmann's scientific activity. First, he wrote a two-volume publication entitled "Physics and Technique of Ultrashort Waves". The second phase of his professional activity during these years was the foundation of the GEMA Company. His research and development at this company and his preliminary works became the ground work and foundation of the development of what has become known as RADAR. All over the world, Hollmann's book is considered the sole predecessor of the world renown Radiation Laboratory series of the Massachusetts Institute of Technology (MIT). Dr. Hollmann's ideas were far ahead of his time, which is disclosed by the fact that his books had only a minute market success during the first years. Later, however, as soon as the importance of ultra-high frequency and microwave principles were applied to television and RADAR, his seemingly minute success turned into the contrary. As people became more and more interested, it was realized that his early books contained the basic foundation for the entire microwave field. 

At this point we recall some facts, not generally publicized, concerning the beginning of RADAR in Germany. As early as 1933 the Institute of Telecommunications in Kiel started work on echo sounding by means of electromagnetic waves. With little experience in this field the Institute bought a magnetron from the Philips Company in Eindhoven, Holland, and began a primitive work. Dr. Hollmann was consulted in both this endeavor and in further studies at the Institute.

As an expert in the field of microwaves and familiar with the methods of Heaviside sounding, Hollmann developed high-energy pulsing devices with broadband amplification and display of the echo signal on the screen of the CRO. When the members of the German Polar Expedition returned home in mid 1933 they brought with them a pulse generator for microsecond-pulses which they had developed during the long Polar night. Hollmann introduced this device at GEMA. Through this device, GEMA had great success and was prominent in this field. In the second volume of his book, Dr. Hollmann deals with the subject of microwave telemetry. The title of one chapter in this volume was "Seeing by Means of Electromagnetic Waves". This title, written in 1935 prior to the development of RADAR was a clear vision of things to come. The original manuscript of this book contained many details and techniques, such as, echo time measurements with a CRO. These details, however, were suppressed by the Navy censors due to severe security regulations at that time. Even so, however, an expert in this and related fields could understand and keep pace with the progress in Germany. Professor Hershberger of the University of California, in his famous memorandum to the American Government, told of the progress in Germany in the field of RADAR and referred to Dr. Hollmann's pioneering in this field. Through Professor Hershberger's efforts the development of RADAR was started in the United States.During the 30's Dr. Hollmann was not willing to give in to the rulers of Germany in order to become a professor at the University. Thus he founded his private "Laboratory for High-Frequency Techniques and Electromedicine". In the next few years he published more than 100 scientific papers. In close cooperation with his brother, Medical Doctor W. Hollmann, he developed new registration methods for electrocardiography. Among their developments were a threephase "Triograph" and an "Absolute-Cardiograph" eliminating the rotation of the bioelectric heart vector and thus displaying the magnitude of the bioelectric emf inside the heart. In the beginning, the work of the Hollmann brothers was looked upon with skepticism but now has been recognized and greatly acclaimed, especially in the USA. In 1942, Dr. Hollmann became Director of the "Research Society: for Radio and Movie". In this position he supervised many laboratories and research institutes throughout Europe. Due to his strong character and his political and economic independence from the rulers of that period, Dr. Hollmann was able to provide refuge for many scientists of countries occupied by the German army and save them from being deported to Germany. As an example, he granted the Kammerlingh-Onnes Institute in Leydon, Holland, a top priority research contract for the study of the development properties of photographic film at very low temperatures and prevented the entire institute and its scientists from being deported to Germany. When his home and his laboratory in Berlin were destroyed he moved his family and his scientific colleagues to Thuringia and continued his research work there. However, since he was not allowed to continue his studies in the field of microwaves, he dedicated himself to such projects as: transient time oscillography, dynamic electron ballistics, radiation diathermy, dielectric and induction heating with spark transmitters and pulses, capacitive AC generators, electromagnetic and electrostatic suspensions of three-dimensional systems, automatic tuning of transmitters and receivers and frequency modulation by means of ferroelectric capacitors, and the like. At the end of the war Dr. Hollmann became a professor of physics at the Friedrich-Schiller University in Jena. Later, when Thuringia was surrendered to Russia, he accepted an offer from the U. S. Government to continue his work in the United States. Together with his family he established his new home in California. There he has continued work in his usual energetic way, and has devoted himself especially to transistors. The results of his research studies in the field of transistors have been published in many scientific magazines, periodicals, and books. A few of the more important topics of his work have been free transistor oscillations similar to the Barkhausen's electron oscillations; powering transistor devices by means of photo-elements, sun batteries, and high frequency energies of high power transmitters, tandem transistors similar to twin electronic tubes, etc. Dr. Hollmann is now Director of a Research Laboratory of Dresser Industries in California and is concerned, among other things, with the direct conversion of heat, light, and atomic energy into low and high frequency AC. His merits in the field of electronics and medical electronics have been appreciated all over the world. In 1952 he was awarded the grade of "Fellow" by the Institute of Radio Engineers. As one of the oldest contributors to the "Magazine for High-Frequency Techniques and Electroacoustics", Dr. Hollmann will never be forgotten for his unswerving sense of justice and right, his humor and calmness and the help he and his wife provided during the war in taking care of his scientific colleagues. We wish him, as an American citizen, on his 60th anniversary, many more years of activity and enthusiasm in pursuit of humanitarian and scientific achievements.


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