How radar works?

Early radar systems were capable only of detecting targets and making a crude measurement of the distance to the target. As radar technology evolved, radar systems could measure more and more properties. Modern technology allows radar systems to use higher frequencies, permitting better measurement of the target’s direction and location. Advanced radar can detect individual features of the target and show a detailed picture of the target instead of a single blurred object.
Most radar systems operate in frequencies ranging from the Very High Frequency (VHF) band, at about 150 MHz (150 million Hz), to the Extra High Frequency band, which may go as high as 95 GHz (95 billion Hz). Specific ranges of frequencies work well for certain applications and not as well for others, so most radar systems are specialized to do one type of tracking or detection. The frequency of the radar system is related to the resolution of the system. Resolution determines how close two objects may be and still be distinguished by the radar, and how accurately the system can determine the target’s position. Higher frequencies provide better resolution than lower frequencies because the beam formed by the antenna is sharper. Tracking radar, which precisely locates objects and tracks their movement, needs higher resolution and so uses higher frequencies. On the other hand, if a radar system is used to search large areas for targets, a narrow beam of high-frequency radar will be less efficient. Because the high-power transmitters and large antennas that radar systems require are easier to build for lower frequencies, lower frequency radar systems are more popular for radar that does not need particularly good resolution.