Is RADAR considered an active or passive remote sensing system?

RADAR is considered an active remote sensing system because it emits its own signals in the form of radio waves and then measures the return signals that bounce back from objects or features in the environment. This self-initiated signal allows RADAR to gather information about the distance, speed, and characteristics of targets, which is a defining characteristic of active remote sensing technologies.

In contrast, passive remote sensing systems do not emit their own signals; instead, they detect and analyze the natural radiation emitted or reflected by the objects they are observing, such as sunlight. Since RADAR actively generates its own electromagnetic energy for sensing, it is classified clearly as an active system, making this choice the correct one.