Proximity fuze

An ammunition fuze that detonates a projectile or missile when it comes near a target, without requiring impact. It senses the target’s presence or distance and triggers the explosive charge.

Radio proximity fuze: A proximity fuze that uses radio waves reflected from a nearby target to trigger detonation. Radio reflection let shells burst near aircraft without direct hits.
World War II: A global war fought from 1939 to 1945 between the Axis powers and the Allied powers. The fuze was developed and deployed during this war.
Anti-aircraft warfare: Military operations intended to defend against attacks by aircraft. Proximity fuzes let shells burst near aircraft rather than requiring a direct hit.
VT fuze: The Allied wartime designation for radio proximity fuzes used in artillery and other ammunition. Its battlefield use demonstrated the advantage of detonation near a target.
Doppler effect: The change in a wave’s observed frequency caused by relative motion between its source and observer. Some radio fuzes detect a target through Doppler shifts in reflected signals.
National Defense Research Committee: A United States government body that coordinated scientific research for national defense from 1940 to 1941. It organized early American research on proximity fuzes.
Artillery: Large-caliber weapons that fire projectiles over long distances, along with the branch that operates them. Artillery shells became a major application of proximity fuzes.
Battle of the Atlantic: The prolonged campaign between Allied and Axis forces over control of Atlantic sea routes during World War II. Proximity-fuzed ammunition improved the defense of ships against aircraft.
Radar: A system that detects objects by transmitting radio waves and analyzing their echoes. Radar principles provide a way to sense nearby targets.
Applied Physics Laboratory: A research center at Johns Hopkins University established during World War II for military technology development. Its team led key American radio-fuze development and testing.

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