Excitation of the Terrestrial Wave Guide by Sources in the Lower Ionosphere

Abstract

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 ø to 20 ø . 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%.

ELF and VLF signals radiated by the “polar electrojet antenna”: Experimental results

“…The effective excitation of the earth-ionosphere waveguide provided by an ionospheric dipole source was evaluated by using the method of reciprocity [Ginzbur•t, 1970;Galejs, 1971;Bart and Stubbe, 1984a]. This technique necessitated evaluation of the wave fields in the ionosphere with its associated problems of numerical instability.…”

“…We calculate for a daytime ionosphere at the equator and northsouth propagation an attenuation of 68 dB/Mm. Furthermore, ionospheric sources are very inefficient exciters of the earthionosphere waveguide at low magnetic latitudes [Galejs, 1971]. If their data are to be accepted, then some new mechanism other than waveguide mode theory must be operating for their propagation system.…”

Spherical Harmonic Series Solution for SLF/ELF Field in the Earth–Ionosphere Waveguide/Cavity

“…In the past century, SLF/ELF electromagnetic wave propagation in the Earthionosphere waveguide or cavity was intensively investigated (Wait 1962;Johler and Berry 1962;Galejs 1971Galejs , 1972Bannister 1974Bannister , 1979Chang and Wait 1974;Chu 1974;Carroll and Ferraro 1990;Fraser-Smith and Bannister 1998;Cummer 2000). In preceding chapter, this problem has been addressed specifically.…”

A numerical study of satellite reception of VLF signals using wave guide concepts

“…Nevertheless, there exist no full wave calculations based totally on wave guide concepts which have been compared with satellite data. This is unfortunate, since wave guide principles have been used by several authors [Galejs, 1971; Einaudi and Wait, 1971a, b;Pappert, 1973] to make estimates for the related problem, i.e., signals produced in the earth ionosphere wave guide by satellite-borne sources. In this paper, calculations based totally on wave guide concepts are compared with some northern hemisphere data obtained from the Ogo 4 satellite.…”