Radars are one of the most essential sensors for surveillance and reconnaissance — they radiate electromagnetic waves and extract range, angle, and velocity information from the reflected signals of the target.

Radars can be divided into ground-based, shipborne, or airborne radars depending on their platforms. Radars can also be classified as short-range (less than ten kilometers), medium-range (ten kilometers to approximately hundreds of kilometers) or long-range (more than hundreds of kilometers) depending on their detection ranges.

The Active Electronically Scanned Array (AESA) radar has been developed recently, following the advancement of semiconductor technology. Multi-function radar systems are currently under development which are capable of detection, tracking, and missile guidance.