Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Berlin-Britz transmitter initially used a wire supported between two 30-metre (98 ft) tall wooden poles. This aerial was replaced in 1947 by a 60 m (197 ft) guyed insulated steel framework mast. This mast was replaced in turn in 1948 by two guyed insulated steel framework masts, each with a height of 100 m (328 ft) and which still exist today. These masts were extended in subsequent years so that today they are 160 m (525 ft) and 144 m (472 ft) tall and carry FM radio broadcasting antennas.