Ground dipole

（重定向自Ground antenna）

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.

Ground dipole antenna, similar to the U.S. Clam Lake antennas, showing how it works. The alternating current I is shown flowing in one direction only through the loop for clarity.

Map showing location of the US Navy ELF transmitters. The red lines show the paths of the ground dipole antennas. The Clam Lake facility (left) had two crossed 14 mi. ground dipoles. The Republic facility had two 14 mi. dipoles oriented east-west, and one 28 mi. dipole oriented north-south.

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.

单词	Ground antenna
释义	Ground antenna 英语百科 Ground dipole （重定向自Ground antenna） 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.
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