Imagine you are facing the side of a mountain somewhere in the distance. The principle behind radar may sound confusing at first, but a simple experiment can demonstrate the basics. This purpose led to the acronym RADAR, short for RAdio Detection And Ranging. The system used high-frequency radio waves to detect German planes and calculate their distance. British inventors, aided by research from other countries, developed a rudimentary warning system which could detect objects moving towards the coastline of England. The concept of using radio waves to detect objects goes back as far as 1902, but the practical system we know as radar began in the late 1930s. Many common land-cover types and materials affect the polarity and strength of the radar return differently, which helps in their identification.
The wavelength of the microwave, its polarization (vertical or horizontal orientation) and strength can be controlled at the source and measured when it returns.
Radar is based on the principle of sending very long wavelength radiation (called microwaves) from an antenna, and then detecting that energy after it bounces off a remote target. Radar (short for 'Radio Detection And Ranging'), which can be airborne or space borne, has greatly changed the way we see the land and ocean surfaces. Radar, like sonar and seismology, uses a man-made pulse of radio energy to map distance based on the length of time it takes the pulse to return from the source.
How does radar and the Doppler system work?