Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio waves or microwaves that bounce off any object in their path. The object returns a tiny part of the wave’s energy to a dish or antenna that is usually located at the same site as the transmitter.
Marine radars are used to measure the bearing and distance of ships to prevent collision with other ships, to navigate, and to fix their position at sea when within range of shore or other fixed references such as islands, buoys, and lightships. In coastal water, port or in harbour, vessel traffic service radar systems are used to monitor and regulate ship movements in busy waters.
As VHF, a VTMS radar is dependent on the radar antenna height when it comes to range. The higher, the farther reach. A Radar transmitter is built in connection with the radar antenna. However, the radar signals may be transported to a traffic terminal, by link or line.