Early Dutch radio astronomy after Second World War. During the Second World War, the German army created the Atlantic Wall along the entire European coast, from Norway, through Denmark, the Netherlands, Belgium and France. Part of this Kammhuberlinie were overlapping radar stations, using the so-called Wurzburg Riese radar antennas. After the War, several of the antennas were confiscated by PTT, the Dutch Telecommunication service. Some, such as the one seen here, were brought to the radio station at Kootwijt, in the East Netherlands. PTT gave one to the Dutch Association for Radio Emission from the Sun and the Milky Way (now ASTRON). On 11 May 1951, with this antenna, Lex Muller confirmed the detection of 21-centimetre emission from atomic hydrogen in our Milky Way galaxy, six weeks after Harold Ewen found it with his feed horn at Harvard. Photographed in 1967.