3-428: The AN/APQ-181 is an all-weather, low probability of intercept (LPI) phased array radar system designed by Hughes Aircraft (now Raytheon ) for the U.S. Air Force B-2A Spirit bomber aircraft. The system was developed in the mid-1980s and entered service in 1993. The APQ-181 provides a number of precision targeting modes, and also supports terrain-following radar and terrain avoidance . The radar operates in
6-653: The K u band (a subset of the J band ). The original design uses a TWT -based transmitter with a 2-dimensional passive electronically scanned array (PESA) antenna . In 1991, the B-2 Industrial Team (including Hughes as a major subcontractor) was awarded the Collier Trophy in recognition of the "design, development, production, and flight testing of the B-2 aircraft, which has contributed significantly to America's enduring leadership in aerospace and
9-566: The country's future national security." In 2002, Raytheon was awarded a contract to develop a new, active electronically scanned array (AESA) version of the APQ-181. This upgrade will improve system reliability, and will also eliminate potential conflicts in frequency usage between the B-2 and commercial satellite systems that also use the J band. In 2008 the Federal Communications Commission accidentally sold
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