The W band of the microwave part of the electromagnetic spectrum ranges from 75 to 110 GHz, wavelength ≈2.7–4 mm. It sits above the U.S. IEEE-designated V band (40–75 GHz) in frequency, and overlaps the NATO designated M band (60–100 GHz). The W band is used for satellite communications, millimeter-wave radar research, military radar targeting and tracking applications, and some non-military applications.
A number of passive millimeter-wave cameras for concealed weapons detection operate at 94 GHz. A frequency around 77 GHz is used for automotive cruise control radar. The atmospheric radio window at 94 GHz is used for imaging millimeter-wave radar applications in astronomy, defense, and security applications.
Less-than-lethal weaponry exists that uses millimeter waves to heat a thin layer of human skin to an intolerable temperature so as to make the targeted person move away. A two-second burst of the 95 GHz focused beam heats the skin to a temperature of 130 °F (54 °C) at a depth of 1⁄64 of an inch (0.40 mm). The United States Air Force and Marines are currently using this type of Active Denial System.[1]
In terms of communications capability, W band offers high data rate throughput when used at high altitudes and in space. (The 71–76 GHz / 81–86 GHz segment of the W band is allocated by the International Telecommunication Union to satellite services.) Because of increasing spectrum and orbit congestion at lower frequencies, W-band satellite allocations are of increasing interest to commercial satellite operators, although no commercial project has yet been implemented in these bands.
Appleby, Roger; Anderton, Rupert N.; Thomson, Neil H.; Jack, James W. (2004). "The design of a real-time 94-GHZ passive millimetre-wave imager for helicopter operations". In Appleby, Roger; Chamberlain, J. Martyn; Krapels, Keith A. (eds.). Passive Millimetre-Wave and Terahertz Imaging and Technology. Vol. 5619. p. 38. doi:10.1117/12.581336.
Chen, Zhiming; Wang, Chun-Cheng; Yao, Hsin-Cheng; Heydari, Payam (2012). "A BiCMOS W-Band 2×2 Focal-Plane Array with On-Chip Antenna". IEEE Journal of Solid-State Circuits. 47 (10): 2355–2371. Bibcode:2012IJSSC..47.2355C. doi:10.1109/JSSC.2012.2209775.
Gilreath, Leland; Jain, Vipul; Heydari, Payam (2011). "Design and Analysis of a W-Band Si Ge Direct-Detection-Based Passive Imaging Receiver". IEEE Journal of Solid-State Circuits. 46 (10): 2240–2252. Bibcode:2011IJSSC..46.2240G. doi:10.1109/JSSC.2011.2162792.
