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Excitation of the Terrestrial Wave Guide by Sources in the Lower Ionosphere
Author(s) -
Galejs Janis
Publication year - 1971
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs006i001p00041
Subject(s) - ionosphere , earth's magnetic field , dipole , physics , daytime , magnetic dipole , geophysics , excitation , computational physics , transverse plane , electric field , geodesy , magnetic field , geology , atmospheric sciences , quantum mechanics , structural engineering , engineering
The effectiveness of a dipole source within the ionosphere is determined relative to a ground based source of the same dipole moment. The earth‐to‐ionospheric cavity is excited best if dip angles of the geomagnetic field are in excess of 15° to 20°. In the optimum orientation the axes of electric and magnetic dipoles are transverse to the geomagnetic field; axial electric dipoles are particularly ineffective. For frequencies in the VLF range the relative effectiveness of an ionospheric source is about 10% at nighttime and 1% at daytime. In the ELF range the relative effectiveness is from 20 to 100%.