How does "Active" radar differ from "Passive" radar?

Active radar operates by sending out its own signals, which then bounce off objects, such as aircraft, and return to the radar system. This process allows operators to determine the distance, speed, and direction of the objects in its radar coverage. Because it generates its own transmission, it can provide real-time, accurate tracking of aircraft within its range.

In contrast, passive radar does not emit any signals of its own; instead, it relies on detecting and analyzing signals that are already being emitted by various sources, such as aircraft transponders, or reflections of existing signals from other systems. This allows passive radar to operate undetected, as it does not reveal its location or intent through active transmission.

This fundamental difference in how active and passive radar systems operate is what defines their respective functionalities and applications. Active radar is generally seen in systems used for air traffic control and surveillance, while passive radar is often used in various military and security contexts.