File:Nauen umbrella antenna 1907.jpg

English: A large umbrella antenna used as the transmitting antenna for the transatlantic wireless telegraphy radio station, Nauen Transmitter Station, built by Gesellshaft fur Drahtlose Telegraphie at Nauen, Germany in 1906, which served as Germany's main communication channel with other nations during World War 1. It consisted of a steel truss tower 100 meters (328 feet) tall, insulated from the ground, attached to the transmitter, with a radial network of cables extending diagonally from the top, anchored to the ground at a distance of 200 m from the tower. The bottom end of the 162 umbrella cables were attached to the three ground anchors with hemp ropes, so the umbrella was insulated from the ground. The surface area of the umbrella was 60,000 square meters (646,000 sq. ft. or about 15 acres). The Nauen spark transmitter had an input power of 35 horsepower (26 kilowatts) and radiated in the very low frequency band. The vertical tower served as an electrically short monopole mast radiator and the radial cables served as a capacitive top load to increase the current in the radiator. The other side of the transmitter was connected to a ground (Earth) system consisting of 108 buried cables radiating from the tower, covering 126,000 square meters or about 31 acres.