High Quality Content by WIKIPEDIA articles! 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 ELF frequency range of 3 Hz to 3 kHz. 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.