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A Numerical Investigation of Classical Approximations Used in VLF Propagation
Author(s) -
Pappert Richard A.,
Gossard Earl E.,
Rothmuller Ilan J.
Publication year - 1967
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 - 10.1002/rds196724387
Subject(s) - ionosphere , computational physics , curvature , physics , radio propagation , exponential function , mathematical analysis , mathematics , geophysics , geometry , astronomy
A computer program based on formalism developed by Budden will be used to evaluate the adequacy of some approximations that have been used in VLF waveguide propagation studies. The program makes allowance for the inhomogeneity and anisotropy of the lowest part of the ionosphere, allows for earth curvature, and may be used for arbitrary direction of propagation at any latitude. The results of this program will be compared with calculations of Wait and Spies who used a model ionosphere consisting of an exponential variation for both electron density and collision frequency. This comparison will allow us to demonstrate a close numerical equivalence between the modified refractive index formulation and the spherical coordinate formulation as implemented by Wait and Spies. Also, it will be shown that an approximation introduced by Wait and Spies during the course of applying the effective surface impedance concept, though quite valid for first‐order mode calculations, is inadequate for daytime second‐order mode calculations.