Imaging radar
Encyclopedia
Traditional radar
sends directional pulses of electromagnetic
energy and detects the presence, position and motion of an object (such as an aircraft
) by analyzing the portion of the energy reflected from the object back to the radar station. Imaging radar attempts to form a picture of the object as well, by mapping the electromagnetic scattering coefficient onto a two-dimensional plane. Objects with a higher coeficient are assigned a higher optical reflective index, creating an optical image.
Several techniques have evolved to do this. Generally they take advantage of the Doppler shift caused by the rotation or other motion of the object and by the changing view of the object brought about by the relative motion between the object and the back-scatter that is perceived by radar of the object (a plane) flying over the earth. Through recent improvements of the techniques, this can be precisely calculated. Imaging radar has been used to map the Earth, other planets, asteroids, other celestial objects and to categorize targets for military systems.
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
sends directional pulses of electromagnetic
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
energy and detects the presence, position and motion of an object (such as an aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
) by analyzing the portion of the energy reflected from the object back to the radar station. Imaging radar attempts to form a picture of the object as well, by mapping the electromagnetic scattering coefficient onto a two-dimensional plane. Objects with a higher coeficient are assigned a higher optical reflective index, creating an optical image.
Several techniques have evolved to do this. Generally they take advantage of the Doppler shift caused by the rotation or other motion of the object and by the changing view of the object brought about by the relative motion between the object and the back-scatter that is perceived by radar of the object (a plane) flying over the earth. Through recent improvements of the techniques, this can be precisely calculated. Imaging radar has been used to map the Earth, other planets, asteroids, other celestial objects and to categorize targets for military systems.
See also
- Synthetic aperture radarSynthetic aperture radarSynthetic-aperture radar is a form of radar whose defining characteristic is its use of relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional...
- Imaging Radars