The principles RADAR was invented by Nikola Tesla in 1917. But it wasn’t built until 1934.
The same year it was used to detect an air raid. It was good because of how fast it detected the planes.
But the British used it as a aircraft detection fully first during WW2. They used it because they believed the Germans were building “death rays.”
The war started research to find better resolution, more portability and more features for radar. The post-war years have seen the use of radar in fields as diverse as air traffic control, weather monitoring, and astrometry and road speed control.
RADAR is a detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for radio detection and ranging.
The word RADAR is now apart of the English Language and it has now lost it capitalisation. It is the only word in the English language that is both an acronym and a palindrome.
A radar system has a transmitter that emits microwaves or radio waves. These waves are in phase when emitted, and when they come into contact with an object are scattered in all directions. The signal is thus partly reflected back and it has a slight change of wavelength if the target is moving.
This enables radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect.
Radar absorbing material, containing resistive and sometimes magnetic substances, is used on military vehicles to reduce radar reflection. This is the radio equivalent of painting something a dark color.
Radar waves scatter in a variety of ways depending on the size of the radio wave and the shape of the target. If the wavelength is much shorter than the target's size, the wave will bounce off in a way similar to the way light is reflected by a mirror. If the wavelength is much longer than the size of the target, the target is polarized, like a dipole antenna.
When the two length scales are comparable, there may be resonances. Early radars used very long wavelengths that were larger than the targets and received a vague signal, whereas some modern systems use shorter wavelengths that can image objects as small as a loaf of bread.
Short radio waves reflect from curves and corners, in a way similar to glint from a rounded piece of glass. The most reflective targets for short wavelengths have 90° angles between the reflective surfaces.
These corner reflectors are commonly used as radar reflectors to make otherwise difficult-to- detect objects easier to detect.
Detection and Search RADAR Targeting RADAR Triggers Weather sensing RADAR system Navigational RADAR Mapping RADAR Road RADAR RADAR for biological research