Active sensors are devices that emit their own energy, such as radio waves or light, to detect objects and gather information about their surroundings. They work by sending out a signal and measuring the energy that bounces back after hitting an object. This allows them to create detailed images or data about the environment, making them useful in various applications like radar and LiDAR. These sensors are commonly used in fields like meteorology, geology, and automotive technology. For example, in self-driving cars, active sensors help detect obstacles and navigate safely by continuously scanning the environment and processing the reflected signals.