AN/APQ-181

The APQ-181 provides a number of precision targeting modes, and also supports terrain-following radar and terrain avoidance.

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 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.

In 2008 the Federal Communications Commission accidentally sold the APQ-181 frequency to a commercial user resulting in the need for installing new radar arrays at a cost of over $1 billion.