EXTRA BONUS FACT: Typical radar can only send out radio waves in one direction at a time, which is why a doppler radar "sweeps" around in order to see in all directions. MinutePhysics is on...
========== Radio Detection And Ranging (RADAR) works by broadcasting radio waves out and then detecting reflections off of objects.The time it takes the signal to return tells us the distance, and the Doppler shift tells how fast the object is moving relative to us.