ELF radiation and propagation

The ELF radiation characteristics of a horizontal wire antenna (HWA) are studied and antenna performance predictions are derived using a simplified "image theory" approach. These performance predictions are substantiated by the results of a 1962 full scale ELF radiation experiment using a transmitting antenna consisting of a 50 mile length of power line located over low conductivity precambrian rock between Cheyenne and Larmie, Wyoming. The transmitting antenna was energized with 200 amperes of single phase 60 Hz current. Electric and magnetic field strengths were measured over an area within a 200 mile radius of the transmitting antenna as well as at a selected "low noise" receiving site 1000 miles away in the Los Padres National Forest, California. Using the "image theory" analysis and accounting for the ELF propagation characteristics of the earth-iononsphere waveguide, the calculated near field and far field values are shown to be consistent with the experimental results.