to the Applied Physics Laboratory, formed by Johns Hopkins University. During the war, some 22 million VT fuses for several calibres of shell were manufactured. Centimeter From 1941–1945, many different microwave radar types were developed in America. Most originated in the Rad Lab where some 100 different types were initiated. Although many companies manufactured sets, only Bell Telephone Laboratories (NTL) had major involvement in development. The two primary military research operations, NRL and SCL, had responsibilities in component development, system engineering, testing, and other support, but did not take on roles for developing new centimetric radar systems. Operating under the Office of Scientific Research and Development, an agency reporting directly to President Franklin Roosevelt, the Rad Lab was directed by Lee Alvin DuBridge with the eminent scientist Isidor Isaac Rabi serving as his deputy. E. G. "Taffy" Bowen, one of the original developers of RDF and a member of the Tizard Mission, remained in the U.S. as an adviser. The Rad Lab was assigned three initial projects: a 10 cm airborne intercept radar, a 10 cm gun-laying system for anti-aircraft use, and a long-range aircraft navigation system. The cavity magnetron was duplicated by the Bell Telephone Laboratories (BTL) and placed into production for use by the Rad Lab in the first two projects. The third project, based on directional homing technology, ultimately became LORAN. It was conceived by Alfred Lee Loomis, who had helped form the Rad Lab. Initially, the Rad Lab built an experimental breadboard set with a 10 cm transmitter and receiver using separate antennas (the T-R switch was not yet available). This was successfully tested in February 1941, detecting an aircraft at a range of 4 miles. The Rad Lab and BTL also improved magnetron performance, enabling the device and associated systems to generate higher wavelengths. As more frequencies were used, it became common to refer to centimeter radar operations in the following bands: P-Band – 30-100 cm (1-0.3 GHz) L-Band – 15-30 cm (2-1 GHz) S-Band – 8-15 cm (4-2 GHz) C-Band – 4-8 cm (8-4 GHz) X-Band – 2.5-4 cm (12-8 GHz) K-Band – Ku: 1.7-2.5 cm (18-12 GHz); Ka: 0.75-1.2 cm (40-27 GHz). There was a gap in the K-band to avoid frequencies absorbed by atmospheric water vapor. These ranges are those given by the IEEE Standards; slightly different values are specified in other standards, such as those of the RSGB. P-Band fire-control After