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Type 277 radar
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Type 277 radar
The Type 277 was a surface search and secondary aircraft early warning radar used by the Royal Navy and allies during World War II and the post-war era. It was a major update of the earlier Type 271 radar, offering much more power, better signal processing, new displays, and new antennas with greatly improved performance and much simpler mounting requirements. It allowed a radar with performance formerly found only on cruisers and battleships to be fitted even to the smallest corvettes. It began to replace the 271 in 1943 and was widespread by the end of the year.
The Type 271 was one of the first microwave frequency radars to enter service, when microwave electronics design was in its infancy. While it was still being fitted to escort ships during 1941 and 1942, great strides in technique were being made in cavity magnetron, waveguide, antenna design and general electronics. Those upgrades that could be easily combined with the existing systems became the 271 Mark IV models, while those that required longer to develop were originally known as the Mark V. Given the magnitude of the changes, in March 1943 the Mark Vs were renamed as the 277 series.
The 277 used a 500 kW magnetron, compared to the 271's 5 kW, added a much higher gain antenna that was stabilized in pitch, replaced the coaxial cable signal feeds with waveguide, and added a plan-position indicator (PPI) system with several remote displays. While the 271 offered performance to about 3 miles (4.8 km) against a U-boat and had to communicate with the commanders by voice tube, the 277 was limited only by the radar horizon and its display could be read directly on the bridge on larger ships.
The 277 spawned several modified versions, including Type 276 for destroyers and Type 293 for dedicated air warning. These were so powerful that they were adapted for other roles by the British Army for coast watching and artillery spotting, and the Royal Air Force as Chain Home Extra Low to counter German aircraft attacking at very low altitude. Improvements to the electronics continued, leading to the P and Q models which arrived in 1945. Q models remained in service well into the 1950s.
The Type 271 was one of the first microwave-frequency radars to reach service, with the first example entering testing in March 1941 and being declared operational in May. At this time, the entire field of microwaves was in its infancy, the requisite cavity magnetron and sealed crystal detectors having been developed only a year earlier. Nevertheless, the 271 proved to be an extremely useful device, small enough to fit on corvettes and having enough optical resolution to detect a U-boat within about 3 miles (4.8 km).
The original Type 271 was intended for small ships where the antenna could be placed directly on the top of the bridge. The operator manually swung the antenna back and forth using a steering wheel connected to a shaft passing through the roof. The Type 272 replaced the shaft with a Bowden cable and updated the electronics to allow it to send its data through as much as 40 feet (12 m) of coaxial cable, intended to allow the antenna to be mounted on the mast of medium-sized ships like destroyers. In practice, the 272 was considered a failure.
The Type 273 was similar to the 272 but replaced the original "cheese" antenna with a much larger parabolic reflector with much higher antenna gain, more than offsetting the signal losses in the coaxial cable. Because this style of antenna had a pencil beam rather than the fan-shaped beam of the cheese-style antenna, in order to keep it aimed at the horizon as the ship pitched and rolled it needed to be mechanically stabilized using a gyroscopic platform. This version was intended for larger ships like cruisers and battleships that had ample room on their mast to install a larger antenna. These proved extremely successful and unstabilized versions were soon picked up by the British Army for coast defense.
While the bulk of the 271 units were being installed, great strides were being made in the electronics related to microwave use. Crystal detectors, a key component needed for practical microwave receivers, were being constantly improved. New models arrived from the United States that were both more robust than the early UK models and had far less electronic noise, from about 20 dB of the early models used in the 271 prototypes, to as little as 14 dB by 1943. The magnetron underwent several rapid improvements in power levels, first into the 100 kW range, and by 1943 was starting to approach 1 MW. These two improvements alone offered the possibility of dramatically increasing the range of a radar system.
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Type 277 radar AI simulator
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Type 277 radar
The Type 277 was a surface search and secondary aircraft early warning radar used by the Royal Navy and allies during World War II and the post-war era. It was a major update of the earlier Type 271 radar, offering much more power, better signal processing, new displays, and new antennas with greatly improved performance and much simpler mounting requirements. It allowed a radar with performance formerly found only on cruisers and battleships to be fitted even to the smallest corvettes. It began to replace the 271 in 1943 and was widespread by the end of the year.
The Type 271 was one of the first microwave frequency radars to enter service, when microwave electronics design was in its infancy. While it was still being fitted to escort ships during 1941 and 1942, great strides in technique were being made in cavity magnetron, waveguide, antenna design and general electronics. Those upgrades that could be easily combined with the existing systems became the 271 Mark IV models, while those that required longer to develop were originally known as the Mark V. Given the magnitude of the changes, in March 1943 the Mark Vs were renamed as the 277 series.
The 277 used a 500 kW magnetron, compared to the 271's 5 kW, added a much higher gain antenna that was stabilized in pitch, replaced the coaxial cable signal feeds with waveguide, and added a plan-position indicator (PPI) system with several remote displays. While the 271 offered performance to about 3 miles (4.8 km) against a U-boat and had to communicate with the commanders by voice tube, the 277 was limited only by the radar horizon and its display could be read directly on the bridge on larger ships.
The 277 spawned several modified versions, including Type 276 for destroyers and Type 293 for dedicated air warning. These were so powerful that they were adapted for other roles by the British Army for coast watching and artillery spotting, and the Royal Air Force as Chain Home Extra Low to counter German aircraft attacking at very low altitude. Improvements to the electronics continued, leading to the P and Q models which arrived in 1945. Q models remained in service well into the 1950s.
The Type 271 was one of the first microwave-frequency radars to reach service, with the first example entering testing in March 1941 and being declared operational in May. At this time, the entire field of microwaves was in its infancy, the requisite cavity magnetron and sealed crystal detectors having been developed only a year earlier. Nevertheless, the 271 proved to be an extremely useful device, small enough to fit on corvettes and having enough optical resolution to detect a U-boat within about 3 miles (4.8 km).
The original Type 271 was intended for small ships where the antenna could be placed directly on the top of the bridge. The operator manually swung the antenna back and forth using a steering wheel connected to a shaft passing through the roof. The Type 272 replaced the shaft with a Bowden cable and updated the electronics to allow it to send its data through as much as 40 feet (12 m) of coaxial cable, intended to allow the antenna to be mounted on the mast of medium-sized ships like destroyers. In practice, the 272 was considered a failure.
The Type 273 was similar to the 272 but replaced the original "cheese" antenna with a much larger parabolic reflector with much higher antenna gain, more than offsetting the signal losses in the coaxial cable. Because this style of antenna had a pencil beam rather than the fan-shaped beam of the cheese-style antenna, in order to keep it aimed at the horizon as the ship pitched and rolled it needed to be mechanically stabilized using a gyroscopic platform. This version was intended for larger ships like cruisers and battleships that had ample room on their mast to install a larger antenna. These proved extremely successful and unstabilized versions were soon picked up by the British Army for coast defense.
While the bulk of the 271 units were being installed, great strides were being made in the electronics related to microwave use. Crystal detectors, a key component needed for practical microwave receivers, were being constantly improved. New models arrived from the United States that were both more robust than the early UK models and had far less electronic noise, from about 20 dB of the early models used in the 271 prototypes, to as little as 14 dB by 1943. The magnetron underwent several rapid improvements in power levels, first into the 100 kW range, and by 1943 was starting to approach 1 MW. These two improvements alone offered the possibility of dramatically increasing the range of a radar system.
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