What does radar transmit information through?

A system that uses the reflection of electromagnetic waves to detect and locate space targets. It can also accurately measure the distance (range) of the target and the speed at which the target approaches or leaves the observation equipment. Radar (the name is the abbreviation of "radio detection and ranging") originated from Hertz's experimental work in the late 1980s. In World War II, British and American researchers developed a high-power microwave radar for military use. Today, radar is used to identify and monitor satellites in Earth orbit, help aircraft and ships navigate, and control air traffic at some important airports.