Echoing across the years: A history of early radar evolution

In this article, we provide a brief history of the evolution of radar across the various regions where the technology's development occurred, often simultaneously and independently. (Note that the original term RADAR, representing "RAdio Detection And Ranging," was devised by the U.S. Navy in 1940.) We cover in detail the years from the late 19th century, when initial experiments were undertaken, through the early 1940s, when many countries sought (often in secrecy) to develop radar during World War II. We then show how the introduction of the resonant cavity magnetron proved a turning point in radar history and end with a short survey of the magnetron's evolution for multiple radar applications.