S. K. Roy (1937-2008) Sitesh Kumar Roy was born in Kolkata on April 30, 1937. He spent his childhood in the district of Rongpur, Bangladesh. He returned to Kolkata with his parents at the age of ten years. He had a brilliant academic career ranking among the first 10 in the School Final and I.Sc. Examinations. After obtaining the B.Sc. (Hons.) degree in Physics from Presidency College in 1957 and the M.Sc. (Tech.) degree in Radio Physics and Electronics from the University of Calcutta with a high 1 st class, he joined the training school of Bhabha Atomic Research Centre, Trombay, Mumbai in 1960 and stood first in the training examination. He joined the Institute of Radio Physics and Electronics on February 7, 1963 as a Research Associate and became a Reader in 1970 and then Professor in 1979. He was the Head of the Department from September 1986 to August 1988. He was also the Program Coordinator of the Centre of Advanced Study in Radio Physics and Electronics from 1994 to 1997. Prof. Roy specialized in the field of microwave properties of semiconductors specifically on Avalanche Transit Time (ATT) Semiconducting Devices. In the mid-eighties, he along with Prof. A. N. Daw and Prof. H. Paria took the initiative to set up a micro-electronics laboratory. In 1986, Prof. Roy as chief investigator, successfully completed a project on the Development of X-, Ku-, and Ka- band Silicon IMPATTs sanctioned by the Department of Electronics, Govt. of India. Prof. Roy successfully guided 15 Ph.D. students and has to his credit more than 200 research papers in reputed journals and conference proceedings and holds two patents on IMPATT oscillators and amplifiers from the Govt. of India. He is the co-author of a book entitled “Microwave Semiconductor Devices (Prentice Hall, 2004) and was invited to write a book chapter in the Encyclopedia of Electrical and Electronics Engineering published by John Wiley, USA (1999). He was a Fellow of IETE, India and a senior member of IEEE, USA. It is due to the untiring effort and indomitable spirit of Prof. S. K. Roy that a Centre of Millimetrewave Semiconductor Devices & Systems, a joint venture between DRDO and the University of Calcutta, was established in 2006. He was the Founder Director of this centre till the last days of his life. He breathed his last on October 18, 2008. His death has left a void in the scientific community of India.