What happens to the radar frequency when an object moves towards it?

When an object moves towards a radar source, the frequency of the radar waves reflected off that object increases due to the Doppler effect. This phenomenon occurs because the waves are compressed as the object approaches the radar source, leading to a higher frequency. The change in frequency can be calculated to determine the speed of the object relative to the radar.

This principle is crucial in law enforcement, particularly when using radar for speed enforcement. Officers use this increase in frequency to accurately determine how fast a vehicle is traveling toward them. The Doppler effect is a reliable method for measuring speed and is foundational to the functioning of radar technology in various applications, including law enforcement and aviation.