Accession Number : AD0635939

Title :   MAGNETIC DIRECTION DEPENDENCE OF THE VLF PHASE VELOCITY FOR THE FIRST TWO WAVEGUIDE MODES.

Descriptive Note : Research rept.

Corporate Author : SYLVANIA ELECTRONIC SYSTEMS-EAST WALTHAM MASS APPLIED RESEARCH LAB

Personal Author(s) : Galejs, J.

Report Date : JUN 1966

Pagination or Media Count : 32

Abstract : The methods previously reported for the computation of the complex propagation constant for the dominant VLF waveguide mode (n=1) are extended to the second mode (n=2). A stratified cylindrical ionosphere model with axial magnetic field is ued to determine the wave impedances needed in the subsequent iterative procedure which yields the modal propagation constants in the magnetic East to West (EW) and magnetic West to East (WE) directions. The predictions for phase velocity differences between modes n=1 and n=2 can account for the recently reported observations on the magnetic direction dependence of the distance D between interference minima of these modes propagating below the nighttime ionosphere. The individual height variations of the components of the conductivity tensor should be considered, and ionosphere models of exponential height variation of conductivity are not adequate. The phase velocity difference between the two modes is less than one per cent, but it is smallest for EW propagation, so that the mode interference distance is 1000 to 2000 km greater for EW propagation than for WE propagation. (Author)

Descriptors :   (*IONOSPHERIC PROPAGATION, VERY LOW FREQUENCY), IONOSPHERE, ATMOSPHERE MODELS, MAGNETIC FIELDS, CYLINDRICAL BODIES, INTERFERENCE, ELECTRICAL IMPEDANCE

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE