Naval Communication Station Harold E. Holt
Coordinates: 21°48′59″S 114°09′56″E / 21.816405°S 114.16563°E
Naval Communication Station Harold E. Holt is located on the northwest coast of Australia, 6 kilometres (4 mi) north of the town of Exmouth, Western Australia. The town of Exmouth was built at the same time as the communications station to provide support to the base and to house dependent families of U.S. Navy personnel.
The station provides very low frequency (VLF) radio transmission to United States Navy and Royal Australian Navy ships and submarines in the western Pacific Ocean and eastern Indian Ocean. The frequency is 19.8 kHz. With a transmission power of 1 megawatt, it is the most powerful transmission station in the Southern Hemisphere.
The station features thirteen tall radio towers. The tallest tower is called Tower Zero and is 387 m (1,270 ft) tall, and was for many years the tallest man-made structure in the Southern Hemisphere. Six towers, each 304 metres tall, are placed in a hexagon around Tower Zero. The other six towers, which are each 364 metres tall, are placed in a larger hexagon around Tower Zero.
On 3 March 2009, the Defence Materiel Organisation advertised on the AusTender website a tender to construct two new roads at the station. The tender stated the 357 guy wires which support the 13 towers had exceeded their life expectancy and the roads will support the installation of the VLF guy wires. It states: Naval Communication Station Harold E Holt (NCSHEH) is sited on the northernmost tip of the peninsula known as North West Cape. The Very Low Frequency (VLF) antennas are large spider webs of wire supported in a top hat arrangement. The centre tower ‘Tower Zero’, rises to a height of 387.9 metres. The other towers are spread out in two concentric rings around Tower Zero; the towers of the inner ring are 364 metres high while those of the outer ring are 304 metres high. Buried in the ground beneath the antenna array is 386 kilometres of bare copper ground mat.
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