XAF Radar

The XAF was an experimental radar set constructed in 1938, which survived World War II as a historical artifact, and is now placed on exhibit at the Historical Electronics Museum, located in Linthicum, Maryland

The XAF—an experimental radar set that resulted from several years' technical progress by the Naval Research Laboratory (NRL)—was constructed in 1938, following a late February decision to experimentally install a radar set on a major warship. Operating at 200 MHz (1.5 meter wavelength) at a power of 15 kilowatts, the XAF featured a "bedspring"-like antenna about 17 feet square. This was mounted in a rotating yoke that allowed it to scan around the horizon, and to elevate to keep the radio beam parallel to the surface of the water when the ship rolled. This large antenna and yoke had to be strong enough for sea service, while remaining as light as possible to avoid excessive topside weight. Accordingly, the Brewster Aeronautical Corporation (then also building the Navy's first monoplane carrier fighter, the F2A "Buffalo"), was given the job of fabricating a suitable duralumin structure. The XAF's transmitter, receiver and other equipment were fabricated by the NRL.

When development and construction were complete, the XAF was installed on the battleship New York. This work, with the antenna mounted atop the pilothouse (displacing a large optical rangefinder, which was moved to the top of the ship's No. 2 14-inch gun turret) was completed in December 1938. During nearly three months of constant operation, averaging almost twenty hours daily as New York participated in winter maneuvers and battle practice in the Caribbean, the XAF's performance and reliability exceeded expectations. It detected aircraft up to 100 nautical miles (nm) away and ships out to 15 nm. The radar was also employed for navigation and in gunnery practice, giving very accurate range and azimuth direction, allowing for accurate targeting of enemy vessels and detection of nearby land or obstructions even at night or in the fog.

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