AN/SPS-40

AN/SPS-40
Name	AN/SPS-40
Introduced	1960s
Type	Air-search radar
Frequency	L-band
Range	Typical detection ranges vary by target and conditions
Manufacturer	Naval Electronics Systems Command; Westinghouse; RCA
Platform	Surface ship
Country	United States

AN/SPS-40 The AN/SPS-40 is a United States Navy long-range, two-dimensional air-search radar developed during the Cold War for early warning and air traffic surveillance. It entered service in the 1960s and was deployed aboard a wide range of United States Navy surface combatants and auxiliary ships to provide horizon detection against aircraft and missiles during crises such as the Vietnam War and the Cold War. The system’s service life overlapped with contemporaneous systems used by NATO partners, influencing naval sensor suites during the Falklands War era and the later transition to three-dimensional radars.

Development and Design

Development began under programs overseen by the Naval Electronics Systems Command to replace earlier air-search radars such as the AN/SPS-6 and to complement height-finding radars like the AN/SPS-8. Contractors including Westinghouse Electric Corporation and RCA Corporation produced prototypes and production sets. Design goals emphasized increased antenna gain, improved clutter rejection, and greater reliability for operations with carriers of the United States Third Fleet and escort vessels assigned to Atlantic Fleet and Pacific Fleet task forces. The program reflected lessons from operations during the Korean War and the expansion of jet aircraft threats documented in analyses by the Naval Air Systems Command and strategic studies at the Rand Corporation.

Technical Description

The radar operates in the L-band and is a two-dimensional, pulse-based air-search system providing range and bearing but not elevation; height information required separate height-finder radars like the AN/SPS-30 or data from airborne early warning platforms such as the E-2 Hawkeye. Antenna arrays were parabolic or cosecant-squared designs driven by pedestal mechanisms similar to those used in contemporaneous systems on Oliver Hazard Perry-class frigate escorts. Signal processing used moving target indication and pulse compression approaches influenced by work at MIT Lincoln Laboratory and components supplied by firms including General Electric and Hughes Aircraft Company. The shipboard installation integrated with combat information centers modeled on those of the USS Enterprise (CVN-65) and networked into air defense systems developed during exercises like Operation Mainbrace.

Variants and Upgrades

Production variants addressed reliability and electronic countermeasure resilience, leading to models retrofitted with improved transmitters and receivers developed under contracts with companies such as Raytheon and Ford Aerospace. Block upgrades incorporated modular electronics, newer duplexers, and enhanced signal processors informed by research from Naval Research Laboratory and standards from North Atlantic Treaty Organization interoperability efforts. Some later upgrades facilitated linkage with tactical data links and command systems deployed on ships participating in Exercise RIMPAC and integrated air defense demonstrations with allies including Royal Navy and Royal Australian Navy units.

Operational History

The radar saw extensive use during the 1960s–1990s aboard escorts and carriers conducting patrols during the Vietnam War, surveillance during Cold War confrontations in the Mediterranean Sea and North Atlantic Treaty Organization exercises, and contingency operations such as maritime interceptions. Crews aboard vessels assigned to Sixth Fleet and Seventh Fleet used the system for vectoring interceptors and cueing surface-to-air missile systems present on some platforms. The system’s limitations in altitude determination accelerated adoption of three-dimensional radars and airborne sensors used in operations like those supporting the Gulf War coalition maritime task forces.

Deployment and Platforms

Installed on destroyers, cruisers, frigates, amphibious ships, and auxiliary vessels across classes including Ticonderoga-class cruiser predecessors, Fletcher-class destroyer modernizations, and numerous Guided missile frigate platforms, the radar formed a backbone of air surveillance for carrier battle groups and convoys. Deployments spanned homeports from Norfolk, Virginia to San Diego, California and forward bases such as Yokosuka and Naples, Italy, operating alongside systems on allied ships during combined operations with forces like the Royal Canadian Navy and French Navy.

Preservation and Surviving Examples

Decommissioned units have been preserved at naval museums and memorials including exhibits affiliated with the Intrepid Sea, Air & Space Museum, the USS Midway Museum, and various regional maritime heritage centers. Surviving antennas and consoles are found as part of restoration projects at former Naval Air Station museum ships and in collections curated by organizations such as the Naval Historical Foundation and local historical societies that document Cold War naval technology.

Category:Naval radars of the United States Category:Cold War military equipment of the United States