What is a Doppler Radar?

Radars 
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Editorial Team - everything RF

Dec 12, 2019

The Doppler effect states that when a sound or radio wave travels from one object (source) to another object (receiver), the frequency of the wave increases (or decreases) when the objects are moving towards (or away from) each other.

The Doppler radar uses this principle to measure the height and speed of an object. So when a doppler radar transmits a wave towards an object, the change in frequency of the transmitted and the received wave is used to calculate the speed or height of that object. 

There are three different cases (image below):

  • If there is no frequency difference in the transmitted and the returned wave, then both the radar and the object are stationary.
  • If the frequency of the returned wave is lower than the transmitted wave, then the object is moving away from the radar.
  • If the frequency of the returned wave is higher than the transmitted wave, then the object is moving towards the radar.

Doppler radars are used for various applications in satellites, aviation, police speed guns, healthcare, radiology, bistatic radar and meteorology.

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