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RAF Fylingdales BMEWS
The two BMEWS (Ballistic Missile Early Warning System) are collateral sensors in the SSN’s network (as noted above, a third radar in Clear, Alaska is officially classified as a BMEWS radar, although its characteristics are same as a PAVE PAWS radar), and are essentially larger versions of the PAVE PAWS. Located at Fylingdales in Britain (54.36˚N, 0.67˚W) and Thule in Greenland (76.57˚N, 68.32 W˚), these radars’ primary mission is early warning of ballistic missile attack. The radar in Greenland has two faces, providing 240˚ degree azimuthal coverage, while the radar in Britain has three faces, providing 360˚ coverage. Both of these radars have received upgrades that allowed them to be incorporated into the United States’ ground-based national missile defense (GMD) system.
Each radar face is bore-sited at 20˚ above the horizon, and can provide elevation coverage from 3˚ to 85˚. Each octagonal BMEWS radar face has a diameter of about 25.6 m and contains 2,560 active transmit/receive modules (the total number of elements, including passive ones, is 3584). Each face has a peak power of 850 kw and an average power of 255 kw (corresponding to a duty factor of 0.3). The radar’s beam width is about 2.0˚
The BMEWS transmit/receive modules have a maximum duty factor of 30% and can produce pulses with lengths between 0.25 and 16 msec. The BMEWS radars use pulse lengths of 0.3 and 6 (typical) msec. in search and pulse lengths between 1 and 16 msec. in track. Search bandwidth is 0.3 MHz (Britain) and 0.6 MHz (Greenland) and track bandwidths are 5-10 MHz respectively. The radars operate using a 54 msec. resource periods.
BMEWS Performance Claims
3,000 nmi range coverage.
 Donald J. Hoft, “Solid State Transmit/Receive Module for the PAVE PAWS phased array Radar,’’ in Edward D. Ostroff, Michael Borkowski, Harry Thomas, and James Curtis, Solid State Radar Transmitters (Artech; Dedham, Mass., 1985) pp. 246-249 (reprinted from Microwave Journal, October 1978); Michael T. Borkowski, “Solid State Transmitters,” in Merrill Skolnik, ed., Radar Handbook, 2nd. Ed. (McGraw-Hill: New York, 1990), pp. 5-3, 5-8, 5-25, and 5-26.
 U.S. Missile Defense Agency (MDA), Environmental Impact Statement, National Missile Defense System, Appendix H, Upgraded Early Warning Radars Analysis, July 1, 2000, p. H-1-7. Available at: (http://www.mda.mil/global/documents/pdf/env_gmd_eis_append_h.pdf)
 MDA, “Environmental Impact Statement,” p. H-1-8.
 Marvin N. Cohen, “Pulse Compression in Radar Systems,” in Jerry L. Eaves and Edward K. Reedy, eds. Principles of Modern Radar (Van Nostrand Reinhold: New York, 1987), p. 475.; F. Shackford, Technical Seminar, MIT Defense and Arms Control Studies Program.
 MDA, “Environmental Impact Statement,” pp. H-1-8, H-1-9.
 R. Sridharan and Antonio F. Pensa, “U.S. Space Surveillance Network Capabilities,” in C. Bruce Johnson, Timothy D. Maclay and Firooz A. Allahdadi, Image Intensifiers and Applications; and Characteristics and Consequences of Space Debris and Near Earth Objects, Proceedings of SPIE, Vol. 3434, July 1988, pp. 88-100.
 USAF Scientific Advisory Board, p. 9.
 “Pave Paws, BMEWS Radar Site Updates Will Broaden Missile Threat Coverage,” Aviation Week and Space Technology, December 9, 1985, pp. 52, 54.
 Ross Kerber, “Making (Radar) Waves, Boston Globe, July 2, 2001, p. C1.
 Cohen, “Pulse Compression in Radar Systems,”; F. Shackford, Technical Seminar.
 Shackford, Technical Seminar. It is unclear if this applies to BMEWs or PAVE PAWS or both, but is consistent with the 16 msec. maximum pulse length and a 30% duty factor of BMEWS.