section_path: History/During World War II
section_name: During World War II
paragraph_text: During World War II
  
  A key development was the cavity magnetron in the UK, which allowed the creation of relatively small systems with sub-meter resolution. Britain shared the technology with the U.S. during the 1940 Tizard Mission.
  
  In April 1940, Popular Science showed an example of a radar unit using the Watson-Watt patent in an article on air defence. Also, in late 1941 Popular Mechanics had an article in which a U.S. scientist speculated about the British early warning system on the English east coast and came close to what it was and how it worked. Watson-Watt was sent to the U.S. in 1941 to advise on air defense after Japan's attack on Pearl Harbor. Alfred Lee Loomis organized the secret MIT Radiation Laboratory at Massachusetts Institute of Technology, Cambridge, Massachusetts which developed microwave radar technology in the years 1941–45. Later, in 1943, Page greatly improved radar with the monopulse technique that was used for many years in most radar applications.
  
  The war precipitated research to find better resolution, more portability, and more features for radar, including small, lightweight sets to equip night fighters (aircraft interception radar) and maritime patrol aircraft (air-to-surface-vessel radar), and complementary navigation systems like Oboe used by the RAF's Pathfinder.