The U.S. Navy's AN/SPG-55B was a tracking and illumination radar used with beam-riding Terrier missiles and semi-active homing RIM-67 Standard missiles, and it was a major component of the MK76 Fire Control System for fleet and area protection. Early variants were deployed in the mid-1950s, and the system's final deployment came during Operation Desert Storm in the early 1990s. The AN/SPG-55 included a C-band 5 GHz tracking pulse radar and an X-band 10 GHz CW radar for guiding Terrier and SM-2 missiles and for CW Doppler tracking. An 8-foot parabolic antenna served both the C-band and X-band transmitters and the C-band pulse receiver, while separate antennas handled the X-band CW functions and side lobe receivers. The system remained effective in the presence of electronic countermeasures. Terrier ships carried a pair of AN/SPG-55 radars on one or both ends of the ship, and either radar could independently complete the mission. The antenna system here was installed on a rooftop at JHU-Applied Physics Laboratory to develop improvements for the air defense mission, including pulse compression, Doppler techniques, and communication waveforms as Terrier missiles evolved into Standard Missile. The radar was first manufactured by Sperry Gyroscope. The RIM-2 Terrier was a two-stage medium-range naval surface-to-air missile among the earliest such missiles to equip United States Navy ships, while the RIM-67 Standard ER was an extended-range surface-to-air and anti-ship missile that replaced earlier missiles including the Terrier. Both used semi-active homing on CW energy from the SPG-55B. In beam-riding guidance, an antenna directs a narrow radar beam at a target, a launched missile is gathered by the beam when it flies into it, and the missile then follows the beam to the target while the antenna keeps the beam pointed at it.