Efficiency of the Earth--ionosphere waveguide excitation by ELF sources located in an anisotropic ionosphere

Institute of Radio Physics, St. Petersburg State University, St. Petersburg, Russia

Abstract

[1]  This paper is devoted to the problem of excitation of the Earth-ionosphere waveguide by the sources located in an anisotropic ionosphere. The ELF range where a single-mode representation of the field can be applied is considered. The generalized theorem of reciprocity makes it possible to find the relation between the field components excited in the waveguide by electric and magnetic dipoles of various orientation. At the location of the emitters in the field of applicability of the quasi-longitudinal approximation, this relation is described by simple analytical expressions. Some results of calculations characterizing the efficiency of waveguide excitation by horizontal and radial dipoles and applicability of approximate formulae are presented. The dependencies of the efficiency parameters on the frequency, latitude, height of the emitter location, and propagation conditions are analyzed.

Received 5 April 2005; revised 4 July 2006; accepted 24 October 2006; published 31 March 2007.

Keywords: Earth--ionosphere waveguide; ELF radiation; lower ionosphere.

Index Terms: 6964 Radio Science: Radio wave propagation; 2403 Ionosphere: Active experiments; 2471 Ionosphere: Plasma waves and instabilities.