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Radio wave propagation over a nonconstant immittance plane
Author(s) -
Janaswamy Ramakrishna
Publication year - 2001
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 - 10.1029/2000rs002338
Subject(s) - immittance , reflection coefficient , mathematical analysis , mathematics , fourier series , reflection (computer programming) , field (mathematics) , physics , optics , geometry , computer science , electrical engineering , engineering , pure mathematics , programming language
The problem of electromagnetic wave propagation over a horizontal, nonconstant immittance plane, whose immittance value is a function of incident grazing angle, is considered. An equivalent specification of the immittance surface is in terms of its angle‐dependent reflection coefficient. Expressions are provided for the field on a vertical line given the field on a previous vertical line. The vertical line field is initialized at the plane containing the source where its aperture current distribution is specified. Both two‐dimensional and three‐dimensional fields are considered, and the expressions are valid for either polarization. The form of expressions is particularly suited for implementing with the Fourier split‐step algorithm of the parabolic wave equation. Extension to inhomogeneous atmosphere to account for mild atmospheric inhomogeneities is presented. Several examples are considered where the immittance arises from small‐scale and large‐scale surface roughnesses. A numerical procedure is described wherein incomplete or approximate reflection coefficient data are made to conform to the assumptions made in the development of the expressions. This is demonstrated for a surface reflection coefficient which is governed by the Miller‐Brown‐Vegh roughness reduction factor. Numerical results are presented for propagation under ducting conditions over a rough surface for frequencies from HF through microwave.