The 'Polar Electrojet Antenna' as a source of ELF radiation in the earth-ionosphere waveguide

The ELF currents produced in the auroral ionosphere by a powerful HF wave modulated at ELF are first computed using the method of Stubbe et al. The technique of reciprocity is then used to evaluate the efficiency of excitation of the earth-ionosphere waveguide by this extended ionospheric current source. Computations suggest that radiated powers ranging from a few milliwatts at 100 Hz to a few watts at 2.0 kHz can be expected for HF effective radiated powers of 150 MW.