How does radar detect and track aircraft or missiles?

Radar systems detect and track aircraft or missiles by radiating electromagnetic energy into space and analyzing the echoes that reflect off targets. The process involves several key technical functions:1

Detection and Ranging

• Transmission and Reception: A transmitter sends a signal through an antenna. When this beam hits a target, a portion of the energy reflects back to the system.1
• Range Measurement: The distance (range) to a target is calculated by measuring the total time it takes for the signal to travel to the target and back.1
• Signal Processing: A receiver extracts these echoes while rejecting unwanted "clutter," such as reflections from rain or the ground, which could otherwise mask the target.12

Tracking and Velocity

• Angular Direction: The target's direction is determined by the orientation of the antenna when the echo is received.13
• Tracking: By measuring a target's location at successive intervals, the system establishes a track, allowing it to predict the target's future path.12
• Doppler Shift: Many systems use the Doppler effect to measure a target's radial velocity. By detecting shifts in the frequency of the reflected signal, the radar can distinguish moving targets from stationary clutter.4

For specialized missions like ballistic missile defense, systems often employ phased-array antennas, which steer beams electronically to track small, fast-moving objects at extreme ranges.5