English: Central mast of the huge wire trideco antenna of the very low frequency (VLF) naval radio transmitter at Anthorn Radio Station, Anthorn, UK, used by the British Navy to communicate with submerged submarines. This facility was actually under the command of NATO, and in a nuclear war would be used to transmit missile launch orders to ballistic missile submarines. It transmits on 19.6 kHz with a callsign of GQD with output power of 550 kilowatts. The antenna consists of six vertical wire radiators (two are visible in the photo) driven at the base of the mast, attached at the six insulator strings visible to six 2148 foot rhombic-shaped horizontal multiwire toploads. These extend at angles of 60° from the central mast, supported by 12 surrounding masts, giving the antenna the shape of a 6-pointed star when viewed from above. The entire antenna is more than a mile in diameter. The standing waves on the high Q antenna create very high voltages on the topload wires, requiring long insulator strings with corona rings at each end to stand the voltage.