Saturday, November 20, 2010

Entering service in 1963, the AN/SPG-59 was a search and illumination radar that was briefly used by the US Navy in the Typhon missile system, during the Cold War. It had a range of 110 nautical miles and an azimuth of 360ยบ. It could search, track, and guide. The AN/SPG-59 had a wide-band receiver which forwarded its received signals back to the ship. Then, ship's computers calculated the interception coarse and forwarded it back to the missile from an omni-directional antenna. This was similar to the older command guidance system, but avoided the inaccuracies of that system by locating the receiver on the missile, which was closer to the target and therefore saw a stronger signal.

The development of the Typhon/SPG-59 system began 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. Although adding additional radars was possible, it was difficult to arrange as the radars were large and required a clear view of the sky, thus limiting the number of suitable locations. The AN/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.