page_title: Ground dipole
hierarchical_section_title: Ground dipole
caption_attribution_description: English: An aerial view of the U.S. Navy's Clam Lake Extremely Low Frequency (ELF) radio transmitter facility. This transmitted ELF radio signals at a frequency of 76 Hz to communicate with submerged nuclear submarines around the world. The transmitter powered two perpendicular "ground dipole" antennas each consisting of a 14 mile transmission line grounded at each end. Sections of the transmission lines can be seen passing through the forest at lower left. The transmission lines were driven with a current of about 300 amps, which flowed deep in the ground between the ends of the lines, in a huge loop. The input power to the antennas was about 1 megawatt, and they radiated about 2 watts of ELF radiation. The Clam Lake facility became operational in 1985 and was shut down in 2004. This photo was taken in 1982 before it became operational, when it was known as the Wisconsin Test Facility. Location: Clam Lake, Wisconsin (WI) UNITED STATES OF AMERICA (USA)
context_page_description: In radio communication, a ground dipole, also referred to as an earth dipole antenna, transmission line antenna, and in technical literature as a horizontal electric dipole, is a huge, specialized type of radio antenna that radiates extremely low frequency electromagnetic waves. It is the only type of transmitting antenna that can radiate practical amounts of power in the frequency range of 3 Hz to 3 kHz, commonly called ELF waves A ground dipole consists of two ground electrodes buried in the earth, separated by tens to hundreds of kilometers, linked by overhead transmission lines to a power plant transmitter located between them. Alternating current electricity flows in a giant loop between the electrodes through the ground, radiating ELF waves, so the ground is part of the antenna. To be most effective, ground dipoles must be located over certain types of underground rock formations. The idea was proposed by U.S. Dept. of Defense physicist Nicholas Christofilos in 1959.
context_section_description: In radio communication, a ground dipole, also referred to as an earth dipole antenna, transmission line antenna, and in technical literature as a  horizontal electric dipole (HED), is a huge, specialized type of radio antenna that radiates extremely low frequency (ELF)  electromagnetic waves. It is the only type of transmitting antenna that can radiate practical amounts of power in the frequency range of 3 Hz to 3 kHz, commonly called ELF waves A ground dipole consists of two ground electrodes buried in the earth, separated by tens to hundreds of kilometers, linked by overhead transmission lines to a power plant transmitter located between them. Alternating current electricity flows in a giant loop between the electrodes through the ground, radiating ELF waves, so the ground is part of the antenna. To be most effective, ground dipoles must be located over certain types of underground rock formations. The idea was proposed by U.S. Dept. of Defense physicist Nicholas Christofilos in 1959.
  Although small ground dipoles have been used for years as sensors in geological and geophysical research,  their only use as antennas has been in a few military ELF transmitter facilities to communicate with submerged submarines. Besides small research and experimental antennas, four full-scale ground dipole installations are known to have been constructed; two by the U.S. Navy at Republic, Michigan and Clam Lake, Wisconsin, one by the Russian Navy on the Kola peninsula near Murmansk, Russia. and one in India at the INS Kattabomman naval base. The U.S. facilities were used between 1985 and 2004 but are now decommissioned.
caption: The U.S. Navy Clam Lake, Wisconsin ELF transmitter in 1982. Sections of the rights of way for the power lines that make up the two crossed ground dipole antennas can be seen passing through the forest at lower left.
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