Stefan L. Hahn was born in Poznań, Poland on February 20, 1921. He received the Ph.D.degree and the D.Sc. degree in 
radioengineering from the Warsaw University of Technology (Politechnika Warszawska), Warsaw, Poland, in 1958 and 1962, respectively. During the period 1949-1991, he served at the Warsaw University of Technology as a professor and as a head of the Institute of Radioelectronics, the Faculty of Electronics and Information Technology. Since 1991, he was a professor emeritus, actively involved in research concerning the theoretical aspects of radioastronomy.
His scientific interests included also signal and modulation theory, quantum frequency standards and radiocommunication systems. He was the author or co-author of over 100 scientific papers printed in Poland, the United States, England, and in Germany. He had also authored 8 patents and had been a supervisor of 23 Ph.D. theses.
During the period 1981-2010, Prof. Hahn served as a vice-chairman and chairman of the URSI (Union Radio-Scientifique Nationale) Commission A on Electromagnetic Metrology. He was a member of the Polish Academy of Sciences and the New York Academy of Sciences and a life senior member of IEEE.
Passed away on 13th of August 2020.