Radar is technology that _ radio waves _the presence of another object further away. Radar is based on_ detects _. A German man discovered the concept of radar but a British inventor Watson-Watt _ perfected _it. A working radar system was only developed during World War ll in_ Britain _. By 1940, the British built 51_ radar stations _along the coastline of England. The radar stations¬¬¬¬ _ bounced _ radio waves into the air, which hit the approaching German plane. Without_ radar _, many historians argue that Britain could have easily lose the war.