The Naval Research Laboratory developed and built the experimental XAF radar in 1938 and installed it on the battleship USS New York for winter maneuvers in the Caribbean in early 1939. After nearly three months of constant operation, averaging almost twenty hours daily, its performance and reliability exceeded expectations as it detected aircraft up to 100 nautical miles away and ships out to 15 nautical miles. The USS New York's crew used radar for navigation and in gunnery practice, spotting the fall of shot and even tracking projectiles in flight. Admiral A.W. Johnson, commander of the Atlantic Squadron, called the XAF equipment one of the most important military developments since the advent of radio itself. Later in 1939, the Radio Corporation of America reengineered the XAF and put it into production as the CXAM, delivering six sets for installation on six Navy ships, and then produced an improved CXAM-1 with a simplified antenna in greater numbers. After proving itself on the USS New York, the XAF antenna returned to the Naval Research Laboratory for additional experiments. The XAF operated at a frequency of 200 MHZ, its mechanical structure was manufactured by Brewster Aeronautical Corp., it detected large birds during the 1939 test, and its antenna contained 42 half wave radiating elements backed by the same number of reflectors. Because of its size and appearance, sailors called it the flying mattress, and it cost less than $17,000 to design and build.
