What type of signals does RADAR transmit to sense information?

RADAR (Radio Detection and Ranging) operates by transmitting microwave signals. These high-frequency electromagnetic waves allow RADAR systems to detect objects and determine their distance, speed, and other characteristics based on the time it takes for the transmitted signals to bounce back after hitting an object. The microwaves have the advantage of being capable of penetrating through various atmospheric conditions, making them ideal for applications in aviation, meteorology, and military operations.

Microwave signals are part of the electromagnetic spectrum and generally have wavelengths ranging from one millimeter to one meter. This range is effective for detecting a wide variety of objects, including aircraft, ships, and precipitation in weather radar.

Other types of signals mentioned in the options, such as optical, ultrasound, or X-ray signals, do not play a role in RADAR technology. Optical signals rely on visible light, which is unable to penetrate clouds and other visual obstructions like RADAR microwaves can. Ultrasound signals are primarily used in medical imaging and certain metrology applications, and X-ray signals are utilized in imaging for diagnostics rather than for the detection distances and speeds of objects in motion.