Farfield Extremely Low Frequency Propagation Measurements, May 72.

Abstract : From 1-19 May 1972, the New London Laboratory of the Naval Underwater Systems Center measured farfield, extremely low frequency (ELF) horizontal magnetic field strengths in Anchorage, Alaska, and Sondre, Greenland. At the same time, MIT Lincoln Laboratory measured field strengths in Norway, Greece, and Saipan. At each location, the horizontal magnetic field strengths were measured in bands of frequencies centered at 45 Hz and 75 Hz to determine the average attenuation rates and relative excitation factors for daytime propagation. The U. S. Navy ELF Wisconsin Test Facility was the transmitter. The principal conclusion from these measurements is that auroral-zone effects are present at extremely low frequencies. (Author)