A radar system includes a transmitter that transmits radio waves called radar signals in predetermined directions. When they come into contact with are reflected or scattered in many directions generally the object. The radar signals are reflected particularly well for material of high electrical conductivity, especially for most metals, sea water and wet soil. Some of them allow to use the altimeter radar. The radar signals that are reflected at the transmitter are desirable for the radar to operate. If the object moves to or away from the transmitter, there is a slightly equivalent change in the frequency of the radio waves, caused by the Doppler effect.
Receivers usually but not always in the same location as the radar transmitter. Although the reflected radar signals picked up by the receiving antenna are generally very weak, they can be reinforced by electronic amplifiers. More sophisticated signal processing methods for recovering useful radar signals are also used.
The low absorption of radio waves by means of which radars detect objects at relatively long intervals, in which other electromagnetic wavelengths, including visible light, infrared light and ultraviolet light, are too high Attenuated. Meteorological phenomena such as fog, clouds, rain, falling snow and slush that block visible light are generally transparent to radio waves. Some radio frequencies that are absorbed or dispersed by water vapor, raindrops or atmospheric gases (especially oxygen) are avoided in the design of the radar, unless detection is intended.