O P N Calla, M.E. is a former deputy Director at ISRO's Space Applications Centre at Ahmedabad. His contribution in the development of Indian Satellites Bhaskara-I and II and in various SATCOM projects with ATS-6, Symphonie, APPLE Stationer, INTELSAT and INSAT satellites is noteable. He held key positions in many projects. He is a great pioneer in the field of millimeter wave technology & has published more than 200 papers and wrote books in Hindi on space Sciences.