What is Radar

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Radars are systems that detect targets or objects and their ranges or velocities, but can also track targets, identify or classify targets, or image targets. The applications are numerous and include industrial, civil and military systems. Radars are also mounted on robots, vehicles and airplanes. The name Radar itself is an old acronym for RAdio Detecting And Ranging.

1 History of Radar

  • 1904 : Christian Hülsmeyer, patent "Process for reporting distant metallic objects to an observer by means of electric waves"
  • 1940s: Würzburg giant from Telefunken f = 560 MHz, B = 500 kHz, m = 11 t, range: 60-80 km Search and track aircraft
  • 1942 : Frequency hopping method, Hedy Lamarr + George Antheil: using Piano rolls to rapidly change RF frequencies to remotely control torpedoes.

Problem: Synchronizing transmitter and receiver. Solution: synchronously running piano rolls (punch tape). Although no known working device was ever produced, the technology today is the basis for RF standards like Bluetooth and 3G as well as military Radars and communication Radars.

  • 1951: Synthetic Aperture Radar: Enlarging antenna aperture using controlled motion of the system. The method yields high resolution images of objects and landscapes
  • 1970‘s: Georadar and first automotive Radar
  • 1995: first series car with ACC (Mitsubishi)

2 Concept

A Radar transmits electromagnetic waves and receives electromagnetic waves that have been reflected on objects in a region of interest. Most surfaces reflect incoming waves at least partly back towards the source. The reflected waves contain information about the object. This can information include its range, velocity, angular direction, size, and shape. Most Radar systems contain at least a transmitter and receiver, an antenna, and a processor. Today, those parts can all be integrated in a very small silicon chip, which enables Radar systems that also fit a lot new and future use cases.