AN/CPS-1

The AN/CPS-1, also known as the Microwave Early Warning (MEW) radar, was a semi-mobile, S band, early-warning radar developed by the MIT Radiation Laboratory during World War II. It was one of the first projects attempted by the Lab and was intended to build equipment to transition from the British long-wave radar to the new microwave centimeter-band radar made possible by the cavity magnetron. This project, led by Luis Walter Alvarez, became the world's first microwave phased-array antenna.

Deployed to the European Theater in 1944, the MEW proved to be an extremely effective radar against German V-1 flying bombs and V-2 rockets. After the war, the AN/CPS-1 was adopted for use by civil aviation becoming the first radar used to track aircraft on civil air routes in the United States.