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ALTAIR (Radar)
ALTAIR (Advanced Research Projects Agency, ARPA Long-Range Tracking And Instrumentation Radar) is a radar tracking station on Roi-Namur island in the north part of the Kwajalein atoll in the Marshall Islands. It is a high-sensitivity, wide-bandwidth, coherent, instrumentation and tracking radar that is capable of collecting precise measurements on small targets at long-ranges. ALTAIR supports several operating modes, including tracking and signature collection at Very high frequency, VHF and Ultra high frequency, UHF. It is part of a network of contributing radar sensors that perform deep-space tracking.Card Index of Radar Sets in Radartutorial The antenna uses a steerable 150-ft dish (46-m-diameter) and employs a focal point VHF feed and multimode Cassegrain UHF feed in conjunction with a frequency selective su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cassegrain Antenna
In telecommunications and radar, a Cassegrain antenna is a parabolic antenna in which the Antenna feed, feed antenna is mounted at or behind the surface of the concave main parabolic reflector dish and is aimed at a smaller Convex mirror, convex secondary reflector suspended in front of the primary reflector. The beam of radio waves from the feed illuminates the secondary reflector, which reflects it back to the main reflector dish, which reflects it forward again to form the desired wikt:beam, beam. The Cassegrain design is widely used in parabolic antennas, particularly in large antennas such as those in satellite ground stations, radio telescopes, and communication satellites. Geometry The primary reflector is a paraboloid, while the shape of the convex secondary reflector is a hyperboloid. The geometrical condition for radiating a collimated, plane wave beam is that the Feed horn, feed antenna is located at the far focus (geometry), focus of the hyperboloid, while the foc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Research Projects Agency
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Advanced Research Projects Agency (ARPA), the agency was created on February 7, 1958, by President Dwight D. Eisenhower in response to the Soviet launching of Sputnik 1 in 1957. By collaborating with academia, industry, and government partners, DARPA formulates and executes research and development projects to expand the frontiers of technology and science, often beyond immediate U.S. military requirements.Dwight D. Eisenhower and Science & Technology, (2008). Dwight D. Eisenhower Memorial CommissionSource The name of the organization first changed from its founding name, ARPA, to DARPA, in March 1972, changing back to ARPA in February 1993, then reverted to DARPA in March 1996. ''The Economist'' has called DARPA "the agency that shaped the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roi-Namur
Roi-Namur ( ) is an island in the north part of the Kwajalein Atoll in the Marshall Islands. Today, the island is a major part of the Ronald Reagan Ballistic Missile Defense Test Site, hosting several radar systems used for tracking and characterizing missile reentry vehicles (RV) and their penetration aids (penaids). Roi-Namur is a military base of the United States, leased from the Republic of the Marshall Islands; however, defense of the Marshall Islands is the responsibility of the United States through the Compact of Free Association. In 2024, a flooding event caused by wave overtopping made national news in the United States, with dramatic footage of water bursting through a door. Etymology The name of the island was coined after the then-separate islands Roi and Namur. ''Roi'' originates from the Marshallese word ''Ruot'', while ''Namur'' originates from the Marshallese word ''Nim̧ur''. The highest point on the island is called Mount Olympus, and is man-made mound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultra High Frequency
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimetre). Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF ( very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, satellite phones, and numerous other applications. The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
