Frederick Britton Llewellyn (September 16, 1897 - December 10, 1971) was a noted American electrical engineer.
He then studied under Professor Alan Hazeltine at Stevens Institute of Technology, receiving his M.E.
Llewellyn helped develop the first public ship-to-shore telephone service, inaugurated in 1929 on the SS Leviathan.
He and Edwin H. Armstrong designed a sensitive receiver used to detect a radar signal reflected from the Moon (Project Diana).
After the war, he served as a consulting engineer, primarily on military electronics systems, assistant to the President of Bell Telephone Laboratories 1956-1961, affiliate of the Institute of Science and Technology at the University of Michigan 1961-1965, and research director of the Polytechnic Institute of Brooklyn 1965 until retirement in 1967.