AN/SPQ-11
A ship-based PESA radar for tracking ballistic missiles and space objects.
The AN/SPQ-11, known as Cobra Judy, is a passive electronically scanned array (PESA) radar that operated aboard the missile range instrumentation ship USNS Observation Island (T-AGM-23). Its tasks included tracking objects in space, monitoring ballistic missiles, and supporting other instrumentation functions. The U.S. Air Force assigned the code name Cobra Judy to this shipborne phased-array radar, which was built primarily to observe Soviet missile tests, working alongside the land-based Cobra Dane radar and the airborne Cobra Ball aircraft. The "AN/SPQ-11" designation, under the Joint Electronics Type Designation System (JETDS), indicates it is the 11th design of an Army-Navy electronic device for a surface ship special radar system; this naming system now applies to all Department of Defense electronic systems.
Cobra Judy was succeeded by the Cobra Judy Replacement (CJR) program in April 2014. The original platform, USNS Observation Island, was removed from service and stricken from the Naval Vessel Register on March 31, 2014. That same day, the CJR program—whose radars are called Cobra King—achieved initial operating capability aboard USNS Howard O. Lorenzen (T-AGM-25). The ship and its Cobra King radar system were declared operational in August 2014. According to the Naval Sea Systems Command, the U.S. Air Force also took over operational and sustainment duties for the vessel. The inertial navigation system for antenna stabilization and alignment was supplied by iMAR Navigation GmbH, while Raytheon manufactures and maintains the CJR's X-band and S-band radars.
Quick Facts
- Country
- United States
- Introdate
- 1983
- Number
- 1
- Frequency
- 2900–3100 MHz (E\F band)
Facts from the source article.
Lore & Background
The AN/SPQ-11 Cobra Judy was a passive electronically scanned array radar installed aboard the USNS Observation Island, a missile range instrumentation ship. Its primary mission was monitoring Soviet missile tests, operating in conjunction with the land-based phased-array radar Cobra Dane and the Cobra Ball aircraft. The system was used for space tracking, ballistic missile tracking, and other instrumentation tasks.
The original platform, USNS Observation Island, was taken out of service and stricken from the Naval Vessel Register on 31 March 2014. On the same day, the Cobra Judy Replacement program, whose radars are called Cobra King, reached initial operating capability aboard USNS Howard O. Lorenzen (T-AGM-25). The USNS Howard O. Lorenzen, together with her Cobra King radar system, were declared operational in August 2014.
According to the Naval Sea Systems Command, the U.S. Air Force assumed operational and sustainment responsibilities for the ship. The inertial navigation system for the antenna stabilization and alignment was provided by iMAR Navigation GmbH, while Raytheon manufactures and maintains the CJR's X and S-band radars.
Reader's Guide
The AN/SPQ-11 Cobra Judy represents a significant milestone in mobile, ship-based phased-array radar technology, specifically designed for monitoring foreign missile tests. Its deployment on a surface ship allowed the United States to position a high-performance tracking radar in international waters, providing critical data on Soviet ballistic missile developments during the Cold War. The system operated in concert with land-based Cobra Dane and airborne Cobra Ball assets, forming a comprehensive monitoring network.
The replacement of Cobra Judy by the Cobra Judy Replacement program, with its Cobra King radars aboard USNS Howard O. Lorenzen, marked a transition to newer technology while continuing the same strategic mission. The transfer of operational and sustainment responsibilities from the Navy to the Air Force reflected the system's primary role in national intelligence and missile defense. The involvement of Raytheon in manufacturing and maintaining the replacement radars, and the use of a specialized inertial navigation system from iMAR Navigation GmbH, underscore the technical sophistication required for stabilizing and aligning such a large array at sea. Cobra Judy's legacy lies in its demonstration that high-power phased-array radars could be effectively operated from a mobile maritime platform, a capability that continues with its successor.
Did You Know?
- It was installed on the USNS Observation Island (T-AGM-23) missile range instrumentation ship.
- Cobra Judy was the U.S. Air Force code name for the afloat phased-array radar.
- The Cobra Judy Replacement program's radars are called Cobra King.
Frequently Asked Questions
What is AN/SPQ-11?
AN/SPQ-11 is a passive electronically scanned array (PESA) radar that the U.S. Air Force gave the code name Cobra Judy. It was purpose-built as a shipborne phased-array system to observe and track Soviet ballistic missile tests.
What platform carries the AN/SPQ-11 radar?
It is installed aboard USNS Observation Island (T-AGM-23), a missile range instrumentation ship operated by the U.S. Navy. The vessel serves as the dedicated seagoing platform for the Cobra Judy sensor suite.
What does AN/SPQ-11 actually do on a day-to-day basis?
Its core job is tracking objects in orbit and monitoring ballistic missile launches, primarily those of the Soviet Union. It also provides supporting instrumentation data for other range-tracking operations.
How does AN/SPQ-11 relate to the other Cobra radars?
Cobra Judy formed the maritime leg of a three-part network that included the land-based Cobra Dane radar and the airborne Cobra Ball aircraft. Together they gave the U.S. overlapping coverage of Soviet missile test ranges.
What replaced AN/SPQ-11 and on what ship?
The Cobra Judy Replacement (CJR) program succeeded it, fielding new radars designated Cobra King. Those upgraded sensors are mounted on USNS Howard O. Lorenzen (T-AGM-25), which took over the Observation Island's instrumentation role.
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