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Radar is a system that uses radio waves to determine the distance (), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method [1] used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain.
This radar uses radio waves along with horizontal, dual (horizontal and vertical), or circular polarization. The frequency selection of weather radar is a performance compromise between precipitation reflectivity and attenuation due to atmospheric water vapor.
Radio pioneer Guglielmo Marconi noticed radio waves were being reflected back to the transmitter by objects in radio beacon experiments he conducted on March 3, 1899, on Salisbury Plain. [9] In 1916 he and British engineer Charles Samuel Franklin used short-waves in their experiments, critical to the practical development of radar. [ 10 ]
Rádio Radar is a Portuguese local radio station based in Almada, which broadcasts in the Lisbon metropolitan area. It focuses on alternative and indie music. [1] The station started broadcasting on 25 June 2002. Its inaugural day was dedicated to Radiohead, in anticipation of the band's upcoming concerts in Portugal in July of that year. [2]
A Doppler radar is a specialized radar that uses the Doppler ... Continuous-wave radar – Type of radar where a known stable frequency continuous wave radio energy ...
The dipole antenna of a radar altimeter of 1947. A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft.
RAAF AN-FPS-117 radar in 2007. As defined by FS-1037C and ITU Radio Regulations, radiodetermination is: [1] the determination of the position, velocity or other characteristics of an object, or the obtaining of information relating to these parameters, by means of the propagation properties of radio waves. There are two main fields to ...
The change of repetition frequency allows the radar, on a pulse-to-pulse basis, to differentiate between returns from its own transmissions and returns from other radar systems with the same PRF and a similar radio frequency. Consider a radar with a constant interval between pulses; target reflections appear at a relatively constant range ...