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TheAN/APQ-181 is an all-weather,low probability of intercept (LPI)phased arrayradar system designed byHughes Aircraft (nowRaytheon) for theU.S. Air ForceB-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 supportsterrain-following radar andterrain avoidance. The radar operates in theKu band (a subset of theJ band). The original design uses aTWT-basedtransmitter with a 2-dimensionalpassive electronically scanned array (PESA)antenna.
In 1991, the B-2 Industrial Team (including Hughes as a major subcontractor) was awarded theCollier 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 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 theFederal Communications Commission accidentally sold the APQ-181 frequency to a commercial user. This resulted in an additional cost to modify the in-progress AESA upgrade which had a total cost of around $1 billion, although the cost for the frequency change was only a portion of this.[1] All B-2 aircraft are expected to have the upgraded radar by 2010.[2]
In accordance with theJoint Electronics Type Designation System (JETDS), the "AN/APQ-181" designation represents the 181st design of an Army-Navy airborne electronic device forradar special equipment. The JETDS system also now is used to name allDepartment of Defense electronic systems.
