Accession Number : AD0686372

Title :   THE PROPAGATION OF ELF WAVES UNDER NORMAL AND NATURALLY DISTURBED CONDITIONS,

Corporate Author : RAND CORP SANTA MONICA CALIF

Personal Author(s) : Field,E. C.

Report Date : MAR 1969

Pagination or Media Count : 42

Abstract : Theoretical analysis of the propagation of electromagnetic waves in the frequency range 30 Hz to 1000 Hz in the earth-ionosphere waveguide. Full wave methods incorporating the vertical inhomogeneity of the ionosphere are used. The model ionospheres, which correspond to both normal and disturbed (polar cap absorption - PCA) conditions, are chosen to illustrate the sensitivity of the propagation to various ionospheric properties. Attenuation constants and phase velocities pertinent to various models are calculated. In addition, detailed calculations of the height dependences of the electromagnetic fields and Joule heating are presented. Resulting conclusions are drawn as to which ionospheric properties and altitude regions most strongly influence the mode structure in the various cases. For example, it is concluded that ions always dominate ELF propagation under moderately disturbed (PCA) conditions, but under ambient conditions, ions are an important factor only for frequencies lower than a few hundred Hz. (Author)

Descriptors :   (*IONOSPHERIC PROPAGATION, EXTREMELY LOW FREQUENCY), IONOSPHERE, ATMOSPHERE MODELS, ATTENUATION, PHASE(ELECTRONICS), GEOMAGNETISM

Subject Categories : Radiofrequency Wave Propagation
      Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE