Thule BMEWS

Background

 The two BMEWS (Ballistic Missile Early Warning System) are collateral sensors in the SSN’s network 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.

Technical Characteristics

 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.[1]  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.[2]

BMEWS Performance Claims

 3,000 nmi range coverage.[3] 

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This post originally was made by George Lewis and is used with permission.