Type 271 radar

Type 271 radar
Name	Type 271
Caption	The distinctive "lantern" antenna of the Type 271 radar.
Country	United Kingdom
Type	Naval surface-search radar
Frequency	3 GHz
Range	Up to 25 nautical miles
Power	5 kW
Introduced	1941
Number built	~1,000
Manufacturer	Admiralty Signal and Radar Establishment

Type 271 radar. The Type 271 was a pioneering S band naval surface-search and fire-control radar developed in the United Kingdom during the Second World War. It was the first operational centimetric radar to be installed on Royal Navy warships, providing a revolutionary capability to detect surfaced U-boats and small targets like periscopes. Its introduction marked a critical turning point in the Battle of the Atlantic, significantly enhancing the effectiveness of Allied convoy escort groups.

Development

The development of the Type 271 stemmed from urgent wartime needs identified by the Admiralty to counter the severe threat posed by German U-boats. Key research was conducted at the Telecommunications Research Establishment under scientists like John Randall and Harry Boot, who developed the revolutionary cavity magnetron. This compact high-power microwave generator enabled the creation of small, powerful radar sets suitable for fitting on smaller warships. The project was managed by the Admiralty Signal and Radar Establishment, with the first prototype, known as Type 271X, undergoing sea trials in early 1941 aboard the corvette HMS *Orchis*.

Design and Features

The most distinctive feature of the Type 271 was its "lantern" antenna, a cylindrical parabolic reflector enclosed in a waterproof radome made of Perspex. This design protected the sensitive components from the harsh North Atlantic environment. Operating in the S band at a wavelength of 10 cm, it offered far superior resolution and target discrimination compared to earlier metre-wave radars like the Type 286 radar. Its Plan Position Indicator (PPI) scope provided a maplike display of the surrounding sea, allowing operators to distinguish between merchant ships, escort ships, and potential U-boat contacts. The system's ability to detect a submarine conning tower at several miles was a game-changing advancement.

Operational History

The Type 271 entered operational service in March 1941, first fitted to the River-class frigate HMS *Rother*. It proved immediately decisive, with early successes including the detection and destruction of U-570, captured intact and later commissioned as HMS Graph. The radar was instrumental in the victories of famed escort groups like Captain-class frigates under commanders such as Frederick John Walker. Its effectiveness forced Kriegsmarine U-boat commanders to adopt radical new tactics and spurred German development of countermeasures like the Metox radar detector. The Type 271 saw extensive use on vessels from corvettes and destroyers to cruisers throughout key theatres including the Arctic Convoys and the Normandy landings.

Variants and Upgrades

The basic Type 271 design spawned several important variants. The Type 272 was a modified version with the "lantern" mounted on a mast for larger ships, while the Type 273 was a dedicated long-range air-search variant used on capital ships like HMS *King George V*. The Type 277, introduced later, combined height-finding and surface-search functions with a "cheese" antenna. Successive models incorporated improved magnetrons and displays, with the final major development being the Type 271Q, which featured a double-cheese antenna for better performance. These evolutions directly informed postwar British radar designs like the Type 293 radar.

Technical Specifications

The Type 271 operated at a frequency of approximately 3 GHz (10 cm wavelength) in the S band. It had a peak power output of around 5 kilowatts and a practical maximum range against a surfaced U-boat of about 25 nautical miles, though it could detect larger capital ships at greater distances. The antenna rotated at approximately 8 RPM, and the display utilized a PPI with a 5-inch cathode ray tube. The entire system, including the waveguide run, transmitter, and receiver units, was designed for reliability in the demanding conditions of the North Atlantic.

Users and Deployment

The primary user was the Royal Navy, which equipped hundreds of escort ships, including Flower-class and Castle-class corvettes, and larger fleet units. Under the Lend-Lease program, sets were supplied to the Royal Canadian Navy and the United States Navy, where it influenced American designs like the SG radar. Following the war, the Type 271 and its derivatives remained in service with various navies, including the Royal Australian Navy and the Royal New Zealand Navy, throughout the 1950s until replaced by more modern systems.

Category:World War II radars Category:Royal Navy equipment Category:Military electronics of the United Kingdom