An organ-pipe scanner is a system used in some

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

systems to provide scanning in azimuth or elevation without moving the antenna. It consists of a series of

waveguide A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ...

s and

feed horn A feed horn (or feedhorn) is a small horn antenna used to couple a waveguide to e.g. a parabolic dish antenna or offset dish antenna for reception or transmission of microwave. A typical application is the use for satellite television recep ...

s arranged in front of a shaped reflector, each one positioned to reflect the beam in a different direction. The wave guides meet at a central point where a small rotating waveguide feeds the

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...

signal into each of the horns in turn as it rotates past them. The system was found in a number of 1950s and 60's era radars, notably the US's AN/FPS-50 radar used in the BMEWS network, and the High Speed Aerial of the UK's

RX12874 RX12874, also known as the Passive Detection System (PDS) and by its nickname "Winkle", was a radar detector system used as part of the Royal Air Force's Linesman/Mediator radar network until the early 1980s. Winkle passed out of service along wi ...

Passive Detection System. The concept fell from use with the increasing use of phased array, which provided a similar steering mechanism in purely electronic form with no moving parts. A similar concept is the

Foster scanner {{Short description, Type of radar system The Foster scanner, or Variable Path scanner, is a type of radar system that produces a narrow beam that rapidly scans an area in front of it. Foster scanners were widely used in post-World War II radar sy ...

, which is typically found on lower-power systems like

counter-battery radar A counter-battery radar (alternatively weapon tracking radar or COBRA) is a radar system that detects artillery projectiles fired by one or more guns, howitzers, mortars or rocket launchers and, from their trajectories, locates the position on ...

References

* {{cite web , url=http://www.radartutorial.eu/06.antennas/an66.en.html , title=Organ-Pipe Scanner , website=Radar Tutorial Radar