Over the following three decades in Germany, a number of radio-based detection systems were developed but none were true radars. This situation changed before World War II. Developments in three leading industries are described.Kummritz, Herbert; "On the Development of Radar Technologies in Germany up to 1945", in Tracking the History of Radar, ed. by Oskar Blumtritt et al., IEEE-Rutgers, 1994
