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History of Radar

Several inventors, scientists, and engineers contributed to the development of radar which played an important role in the Allied victory in World War II… But how many of us Know What does “RADAR” stands for? The term RADAR was coined in 1941 as an acronym for “Radio Detection and Ranging”. Radar is a 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. A transmitter emits radio waves, which are reflected by the target and detected by a receiver, typically in the same location as the transmitter. Although the radio signal returned is usually very weak, radio signals can easily be amplified. This enables a radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in many contexts, including meteorological detection of precipitation, air traffic control, police detection of speeding traffic, and by the military. It was originally called “RDF” (Radio Direction Finder) in Britain.

In 1842, Christian Johann Doppler, an Austrian physicist and astronomer wrote a paper on the determination of motion using the frequency of light in the study of the movement of stars. His theory named the Doppler Principle, the concept defining how radar determines speed, became the foundation for radar development many years later. In 1888, German physicist Heinrich Hertz while demonstrating James Maxwell’s Electromagnetic Equations using using radio waves discovered that radio waves could be bounced off metallic objects. The potential utility of Hertz’s work as the basis for the detection of targets of practical interest did not go unnoticed at the time.

In 1897, Russian scientist Alexander Popov reported the detection of a warship “Lieutenant Il’in” when it crossed the radio communication link between two other ships “Europe” and “Africa”. This observation was the first mention about the possibility of object detection by means of radio waves. The first to use radio waves to detect “the presence of distant metallic objects via radio waves” was Christian Hülsmeyer, who in 1904 demonstrated the feasibility of detecting the presence of a ship in dense fog, but not its distance. He received Reichspatent Nr. 165546 for his pre-radar device in April, and patent 169154 on November 11 for a related amendment. He also received a patent (GB13170) in England for his “telemobiloscope” on September 22, 1904.
Nikola Tesla, in August 1917, first established principles regarding frequency and power level for the first primitive radar units. Before the Second World War, developments by the Americans (Dr. Robert M. Page tested the first monopulse radar in 1934), the Germans, the French (French Patent n° 788795 in 1934), and mainly the British who were the first to fully exploit it as a defence against aircraft attack (British Patent GB593017 by Robert Watson-Watt in 1935), led to the first real radars. In 1935, Robert Watson-Watt,a Scottish physicist, was asked by the Air Ministry to investigate the possibility of creating a “death-ray” weapon using radio waves  and received a patent for the system and funding for further development.

Hungarian Zoltán Bay produced a working model by 1936 at the Tungsram laboratory in the same vein. In 1934, Émile Girardeau, working with the first French radar systems, stated he was building radar systems “conceived according to the principles stated by Tesla”.

ALTAIR(ARPA Long-Range Tracking and Instrumentation Radar),
A long-range radar antenna, known as ALTAIR (ARPA Long-Range Tracking and Instrumentation Radar), is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein in the Pacific Ocean. It is a high-sensitivity, wide-bandwidth, coherent, instrumentation and tracking radar that is capable of collecting precise measurements on small targets at long ranges. ALTAIR supports several operating modes, including tracking and signature collection at VHF and UHF.

The war precipitated research to find better resolution, more portability and more features for the new defence technology. Post-war years have seen the use of radar in fields as diverse as air traffic control, weather monitoring, astrometry and road speed control.

In this digital age, radar technology has become firmly embedded as a law  enforcement tool. Advances in digital technology in the first decade of the 21st century sparked further improvement in signal and data processing, with the goal of developing (almost) all-digital phased-array radars. Today radar is employed by the military,in law enforcement, weather, aviation,traffic,sports and Space.