Battles & Wars › Between the wars › Radar (and Britain's Chain Home)
Raytheon (radar magnetrons to the Patriot missile)
founded 1922; WWII magnetrons; Patriot in service 1984· Arms maker, factory or program· Arms makers & war industry
Well documentedSolid records, physical evidence or scientific consensus.
Massachusetts electronics firm founded in 1922 that mass-produced radar tubes in World War II and later built the Patriot missile.
See it on the Battles & Wars map →What happened
Founded in Cambridge in 1922 by Laurence Marshall, Vannevar Bush and Charles Smith, Raytheon first made radio tubes. In World War II engineer Percy Spencer found a way to stamp out cavity magnetrons, the heart of microwave radar, instead of machining each one, and Raytheon is credited with about 80% of the Allies' magnetrons. Spencer later invented the microwave oven. After the war it built missiles such as the Sparrow, Hawk and Patriot. Since 2023 its parent company has been called RTX.
Why it matters
It turned laboratory radar into mass-produced equipment and grew into one of the largest US missile makers, part of the postwar military-industrial complex.
How we know
Company records and patents, Radiation Laboratory histories, Pentagon contract data, and Government Accountability Office reports, including those on the Patriot.
Still debated
The popular story that a melted candy bar in Spencer's pocket led him to the microwave oven comes from later retellings, and details vary.
Connections (3)
▸Raytheon (radar magnetrons to the Patriot missile) built radar sets designed by MIT Radiation LaboratoryWell documented
The connection
The MIT Radiation Laboratory, a wartime team of several thousand scientists and staff, designed about half the radars the US used in World War II. It did not mass-produce them. Raytheon, near Boston, was one of the firms that did, building magnetrons and shipboard radar sets such as the SG surface-search radar.
When and how
Cambridge and Waltham, Massachusetts, 1940–45; Rad Lab director Lee DuBridge; Raytheon's Laurence Marshall and Percy Spencer.
How we know
Rad Lab and Navy contract records, the lab's 28-volume technical series, and company histories.
Debates and open questions
Which designs were the Rad Lab's and which were improved by industry engineers is often blurred in the histories of both.
▸Raytheon (radar magnetrons to the Patriot missile) mass-produced most Allied units of the Cavity magnetron and the Tizard MissionMostly agreed
The connection
Britain's Tizard Mission brought the cavity magnetron to the US in September 1940. Each one had to be machined from solid copper. Raytheon's Percy Spencer devised a way to stamp out thin copper layers and join them, raising output from dozens a day to about 2,600 a day. Raytheon is credited with about 80% of Allied wartime magnetrons.
When and how
Waltham and Newton, Massachusetts, 1941–45; Percy Spencer and Raytheon's workforce.
How sure are we?
Spencer's patents and company production records; the figures come mostly from Raytheon's own histories.
Debates and open questions
Sources disagree on the starting rate, from about 17 to 100 a day, and on what the 80% counts: all magnetrons, or only radar ones.
▸Raytheon (radar magnetrons to the Patriot missile) made the Patriot missiles fired in the Gulf War (Operation Desert Storm)Well documented
The connection
Raytheon's Patriot was built to shoot down aircraft and was hastily upgraded to hit ballistic missiles. In 1991 Patriots fired at Iraqi Scud missiles aimed at Saudi Arabia and Israel. Early claims of near-total success fell under scrutiny. At Dhahran, a software timing error stopped one battery from tracking a Scud that killed 28 American soldiers.
When and how
Saudi Arabia and Israel, January–February 1991; US Army Patriot batteries; the Dhahran barracks strike, February 25, 1991.
How we know
US Army statements, congressional hearings in 1992, and Government Accountability Office reports, including one on the Dhahran software failure.
Debates and open questions
Success rates remain disputed: the Army later claimed about 70% in Saudi Arabia, while critics such as MIT's Theodore Postol argued few warheads were destroyed.