Radio stations and systems ITU

Radar is a system that uses radio waves to determine the distance (ranging), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations and terrain. The term RADAR was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging". The term radar has since entered English and other languages as an anacronym, a common noun, losing all capitalization.

thumb|Modern radiosondes showing progress of miniaturisationthumb|A Global Positioning System|GPS sonde, approx 220 × 80 ×75 mm (8.7 × 3.1 × 3 in) (with grounding station in the background, used to perform a 'ground check' and also recondition the humidity sensor)

ground-based visual aid for landing

distress radiobeacon, a tracking transmitter that is triggered during an accident

facility, site or item with transmitter and/or receiver used for radiocommunication

type of radar system used in air traffic control

type of radio station

transmitter-receiver associated with a fixed navigational mark

aircraft guidance system

radar sensor that illuminates a large portion of space with an electromagnetic wave and receives back the reflected waves from targets within that space

geostationary telecommunication station at an altitude of 20–50 km

station operating on frequencies allocated for ham or other non-commercial use

on-shore maritime radio station

horizontal guidance system

type of VHF radio beacon used in aviation