AN/SPG-59

From Wikipedia, the free encyclopedia

The AN/SPG-59 was an advanced phased array radar developed by the U.S. Navy starting in 1958. It was intended to offer search, track and guidance from a single radar system and antenna. Paired with the new Typhon missile, the system was to provide wide-area air defense out to about 110 nm from suitable anti-aircraft cruisers. Both the radar and missile proved to be well beyond the state of the art of the era, and the project was eventually canceled in December 1963.^[1]

The Typhon/SPG-59 started as a response to the introduction of sea-skimming anti-ship missiles into service with Soviet Naval Aviation groups. First-generation missile systems like Talos and Terrier used a combination of beam riding and semi-active radar homing (SARH) that required a special targeting radar to illuminate the target through the entire interception. Typical installations included either two or four such illumination radars, which limited the number of simultaneous interceptions. Facing volleys of missiles such systems could easily be overwhelmed. Adding additional radars was possible, but difficult to arrange as the radars were fairly large and required a clear view of the sky, limiting the number of suitable locations. This led to a "specification convergence"; since there could only be a small number of radars, the missile receivers were built to tune in only a small number of potential "channels". That meant that increasing the number of radars would also require the missiles to be updated as well.

The SPG-59 avoided this problem by acting as both the search and illumination radar. That reduced the problem of siting, as there needed to be only one radar on the ship, albeit a very large one. The Typhon missiles also helped solve this problem, switching from SARH tracking to track-via-missile. In this system the receiver on the missile is a wide-band receiver, and forwards its received signals back to the ship. The ship's on-board computers then calculate the interception coarse and forward it back to the missile from an omni-directional antenna. This is similar to the older command guidance system, but avoids the inaccuracies of that system by locating the receiver on the missile, which is closer to the target and therefore sees a stronger signal. Although this system required the missiles to be able to tune in a number of command radio channels, these are generally much simpler and smaller than radar receivers, allowing a much larger number of channels to be supported.

The project ran into problems almost immediately. The phased array radar required a large number of individual broadcaster elements that proved to be unreliable and very expensive. Additionally, the power requirements of the system were so huge that only nuclear-powered ships could afford to operate the system. Although such ships were then under construction, they were politically controversial. As development dragged on, the system was eventually abandoned in December 1963 in favor of the simpler SCANFAR system.^[1] SCANFAR used a phased-array radar for search, but retained the individual illumination radars for missile guidance. During development, SCANFAR further separated the search and track systems, using separate antennas for each.

In November 1962 USS Norton Sound (AVM-1) was towed to Baltimore, Maryland for installation of the Typhon Weapon Control System, including the AN/SPG-59. The conversion was completed early in 1964, and Norton Sound was recommissioned 20 June 1964 to continue tasks in weapons research. Baltimore was designated homeport for Norton Sound, and for several months she operated in Chesapeake Bay, evaluating the Typhon System. Assigned to Port Hueneme, California in July 1965, she arrived there the last day of that month. During a three month stay at Long Beach Naval Shipyard commencing 15 July 1966, all Typhon equipment was removed following discontinuance of the system.^[2]