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This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. Radar is an acronym for radio detection and ranging. It is a system used to detect, range (determine the distance of), and map objects such as aircraft and rain. Strong radio waves are transmitted, and a receiver listens for any echoes. By analysing the reflected signal, the reflector can be located, and sometimes identified. Although the amount of signal returned is tiny, radio signals can easily be detected and amplified.
Radar radio waves can be easily generated at any desired strength, detected at even tiny powers, and then amplified many times. Thus radar is suited to detecting objects at very large ranges where other reflections, like sound or visible light, would be too weak to detect.
Radar sets attempt to reflect electromagnetic waves, notably radio waves and microwaves, from target objects. This reflection is then detected using a radio receiver.
Electromagnetic waves reflect from any large change in the dielectricMost generally, a dielectric is an insulator, a substance that is highly resistant to flow of electric current. Layers of such substances are commonly inserted into capacitors to improve their performance, and the term dielectric refers specifically to th or diamagnetic constants. This means that a solidA solid is a state of matter, characterized by a definite volume and a definite shape (i. it resists deformation). Within a solid, atoms/ molecules are relatively close together, or "rigid"; however, this does not prevent the solid from becoming deformed object in airAir is a name for the mixture of gases present in the Earth's atmosphere. Compressed air is often used in scuba diving as a shallow water breathing gas and to inflate buoyancy devices. Compressed air is also used as a source of energy for pneumatic tools. or vacuumThe article on the vacuum cleaner is located elsewhere. In physics, a vacuum is the absence of matter in a volume of space. A partial vacuum is expressed in units of pressure. The SI unit of pressure is the pascal (abbreviated to Pa in usage). It can also, or other significant changes in atomic density , will usually reflect radar waves. This is particularly true of electrically-conductive materials such as metalFor alternative meanings see metal (disambiguation). In chemistry, a metal is an element that readily forms cations and has metallic bonds, and it is sometimes said that it is similar to a cation in a cloud of electrons. The metals are one of the three gr, making radar particularly well suited to the detection of aircraft and shipA ship like a boat, is a vehicle designed for passage or transportation by water. A ship usually has sufficient size to carry its own boats, such as lifeboats, dinghies, or runabouts. A rule of thumb saying (though it doesn't always apply) goes: "a boat cs.
Electromagnetic waves do not travel well underwater; thus for underwater applications, sonarAcronyms Sonar so und n avigation a nd r anging) is a technique that uses sound propagation under water to navigate or to detect other watercraft. There are two kinds of sonar, active and passive. Active sonar Active sonar creates a pulse of sound, often, based on sound waves, has to be used instead of radar.
Radar waves reflect in a variety of ways depending on the size of the radio wave and the shape of the target. If the radio wave is much shorter than the reflector's size, the wave will bounce off in a way similar to the way light bounces from a mirror. Early radars used very long wavelengths that were larger than the targets and received a vague signal, whereas modern systems use shorter wavelengths (a few centimetres) that can image objects the size of a loaf of bread or larger.
Radio waves always reflect from curves and corners, in a way similar to glint from a rounded piece of glass. The most reflective targets have 90° angles between the reflective surfaces. A surface consisting of three flat surfaces meeting at a single corner, like the corner on a block, will always reflect directly back at the source. These so-called corner cubes are commonly used as radar reflectors to make otherwise difficult-to-detect objects easier to detect, and are often found on boats in order to improve their detection in a rescue situation. For generally the same reasons objects attempting to avoid detection will angle their surfaces in a way to eliminate corners, which leads to "odd" looking stealth aircraft.
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