John Ashworth Ratcliffe was born in Bacup, Lancashire, 12 December 1902. He was educated at Bacup and Rawtenstall Secondary School, 1912-14; Heversham Grammar School, 1914-19; Giggleswick School, 1919-21; and Sidney Sussex College, Cambridge, 1921-4. He married Nora Disley in 1930, with whom he had two daughters.

He carried out research into radio wave propagation in the Cavendish Laboratory, Cambridge University, 1924-7. He was a University Demonstrator (later Lecturer), 1927-47, and Reader in Physics, 1947-60, Cambridge University, where he headed the radio group at the Cavendish. He was a fellow of Sidney Sussex College, Cambridge, 1927-60. He worked on the development of radar at the Telecommunications Research Establishment, 1939-45. He was Director of the Radio and Space Research Station, Slough, 1960-6. He was editor of the "Journal of Atmospheric and Terrestrial Physics", 1965-76. He retired in Cambridge, 1966. He died on 25 October 1987.

He was awarded the OBE, 1947, and the CBE, 1959. He was an honorary fellow of Sidney Sussex College, Cambridge, 1962-87.

His publications include: "The Physical Principles of Wireless" (1929); "The Magnetoionic Theory and its Applications to the Ionosphere" (1959); editor, "Physics of the Upper Atmosphere" (1960); "Sun, Earth and Radio" (1970); and "An Introduction to the Ionosphere and Magnetosphere" (1972).