Defence or Civil Radar - it-™s a Matter of Wave Propagation

Radar: Some Historical Background
"The history of radar began with the experiments of Heinrich Hertz in the late 19th century, which showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell-˜s seminal work on electromagnetism. But it was not until the early 20th century that systems, able to use these principles, were becoming widely available, and it was the German inventor Christian Hülsmeyer who first used them to build a simple ship detection device, intended to help avoid collisions in fog (Reichspatent Nr.
165546). Numerous similar systems, which provided directional information to objects over short ranges, were developed over the next two decades.- From Wikipedia, the free encyclopaedia.