By early 1917 he had reached the rank of Sergeant and was rescued from likely death by being selected by Lieutenant Richard Courant – a mathematician friend of his father who later married his sister, Nina – to go to German-occupied northern France and assist in developing the earth telegraph [de] (German: Erdtelegraphenapparat), a seismic apparatus.
[1][2][additional citation(s) needed] At the close of the war, Runge, now highly motivated by his adverse military experience, returned to academic studies.
In the summer of 1935, Runge, now Director of Telefunken's Radio Research Laboratory, initiated an internally funded project in radio-based detection technology.
With the antennas placed flat on the ground some distance apart, he arranged for an aircraft to fly overhead and found that the receiver gave a strong Doppler-beat interference signal.
Wilhelm Stepp, an engineer on the research staff, designed a transmit-receive device (a duplexer) for allowing a common antenna.
This led the Luftwaffe (German Air Force) to fund Telefunken for the development of a 50-cm (600-MHz) gun laying system, the Würzburg.
He also slowed progress by creating two separate radar research tracks, one within Telefunken under Hermann Göring's purview and the other under the navy.
[6]: 263 When the great advance of centimetre wave radar neared, Runge argued that it was impractical and insured that research was defunded in 1942.