Dr. Merle Antony Tuve, 80, a physicist who was credited with a major role in the development of the proximity fuze during World War II and a retired director of the Carnegie Institution's department of terrestrial magnetism, died of a heart ailment May 20 at Suburban Hospital. He lived in Chevy Chase.

Dr. Tuve was a native of Canton, S.D. He earned bachelor's and master's degrees at the University of Minnesota. He taught physics at Princeton and Johns Hopkins universities and earned his doctorate at Johns Hopkins in 1926.

While at Johns Hopkins, he and a Carnegie scientist conducted a radio experiment that confirmed the existence of the ionosphere, the electrical sea that exists in the outer limits of the atmosphere. The principles they used later came to have important applications in the development of radar.

Dr. Tuve joined the Carnegie Institution staff in 1926. During World War II, he was on leave with the Office of Scientific Research and Development, where he headed a section engaged in developing antiaircraft weapons. The result of this work was the proximity fuze, an electronic device that detonates a shell in the vicinity of a target. This greatly improved the efficiency of antiaircraft defenses and later was adapted for use on other kinds of weapons.

In 1964, as director of the department of terrestrial magnetism, Dr. Tuve announced the development of an image intensifier that greatly increased the power of telescopes used in astronomy. He retired in 1967.

His honors included a Presidential Medal of Merit and the rank of commander of the Order of the British Empire.

Dr. Tuve was a former editor of the Journal of Physical Research and home secretary of the National Academy of Sciences. He was a member of the American Philosophical Society and the American Academy of Arts and Sciences and other learned societies. He was a trustee of Johns Hopkins University.

Survivors include his wife, Dr. Winifred G. Whitman of Chevy Chase; a daughter, Dr. Lucy T. Comly of Schenectady, N.Y.; a brother, Richard L., of Silver Spring; three grandchildren, and a great-grandchild.