The AN/SPS-55 is a solid state surface search and navigation radar. It was developed by Cardion Electronics for the U.S. Navy under a contract awarded in 1971. It was originally developed for a class of ships known as Patrol Frigates, but it was also installed on numerous Cruisers, Destroyers and Minesweepers. It is an I band radar and its antenna consists of two waveguide slotted arrays mounted back-to-back. One array provides linear polarization and the other provides circular polarization. Polarization is user selectable and the circular polarized array is more effective in reducing returns from precipitation.