Shishirkumar Mitra (1890-1963) was another Calcutta stalwart who pioneered radio research in India and became an authority on ionospheric problems. As Khaira Professor of Physics, he established a wireless laboratory and installed elaborated equipment for the study of atmospherics. He also constructed a radio transmitting station in the Khaira Laboratory, which used to broadcast regular programmes with the call sign 2CZ. It became the training ground in electronic techniques for many of his students. In 1948 he established a separate Department of Radiophysics and Electronics in the University College of Science and Technology, and started a comprehensive M.Sc.(Tech) course. He also established an ionosphere field station at Haringhata, 30 miles north of Calcutta.

Mitra’s chief discovery was of new data on various layers of the ionosphere under Indian conditions by using the pulse technique, and in definitively establishing the existence of a new layer (the D layer) first reported by Appleton in 1928. His treatise ‘The Upper Atmosphere’ became an indispensable reference book on atmospheric research.