Generation of Super Low Frequency Signals at the HAARP Facility for Long Range Propagation

Super low frequency electromagnetic radiation, or SLF, is defined as a frequency range of 30–300 Hz with wavelengths of 10,000-1,000 kilometers, respectively. SLF electromagnetic signals can be guided by the Earth-ionosphere waveguide and propagate over large distances. Since the waves are guided by the lower ionosphere, their propagation characteristics can serve as a diagnostic of the ionosphere's D region. The challenge of employing such waves in a controlled experiment comes down to the signal generation. To radiate such waves with a conventional antenna would require hardware that is many kilometers in length and impractical to build. To get around this limitation, the HAARP facility (High-frequency Active Auroral Research Program) located in Gakona Alaska, can be used to modulate natural overhead currents, known as the electrojet (quasi-DC electric current which flows in the D and E region of the Earth's ionosphere), which causes the upper atmosphere to act as a large antenna anywhere from 30–50 km in length. The HF antenna array at HAARP can produce SLF waves by modulating a high frequency beam at SLF.