Triode were invented, Philipp Lenard used the principle of grid control while conducting photoelectric experiments in 1902. The first vacuum tube used in radio was the thermionic diode or Fleming valve, invented by John Ambrose Fleming in 1904 as a detector for radio receivers. It was an evacuated glass bulb containing two electrodes, a heated filament and a plate (anode). Triodes came about in 1906 when American engineer Lee De Forest and Austrian physicist Robert von Lieben independently patented tubes that added a third electrode, a grid, between the filament and plate to control current. Von Lieben's partially-evacuated three-element tube, patented
John P. Costas (engineer) properties for the problem. Costas was made a fellow of the Institute of Electrical and Electronics Engineers (IEEE) in 1965 for "contributions to communications theory and techniques." Among Costas' most notable publications are the following, John P. Costas (engineer) John Peter Costas (1923 in Wabash, Indiana – 2008) was an American electrical engineer. Costas invented, among other things, the Costas loop and Costas arrays. Costas studied at Purdue University as an undergraduate. During World War II, he was involved in radar engineering, serving in the U.S. Navy as a radar officer. He was a graduate student at Massachusetts Institute of