Journal ArticleDOI
Finite conductivity uniform GTD versus knife edge diffraction in prediction of propagation path loss
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In this paper, the authors proposed to apply wedge diffraction in the format of the geometrical theory of diffraction (GTD), modified to include finite conductivity and local surface roughness effects.Abstract:
Diffraction propagation over hills and ridges at VHF and UHF is commonly estimated using Fresnel knife edge diffraction. This approach has the advantage of simplicity, and for many geometries yields accurate results. However, since it neglects the shape and composition of the diffracting surface, it can in some cases yield results which are in serious disagreement with measurements. To remedy this, attempts have been made to approximate the diffracting hill or ridge by other shapes, most notably cylinders. These approaches have not been widely adopted, due in large part to their greater numerical complexity. In this paper it is proposed to apply wedge diffraction in the format of the geometrical theory of diffraction (GTD), modified to include finite conductivity and local surface roughness effects. It is shown that, for geometries with grazing incidence and/or diffraction angles, significant improvement in accuracy is obtained. Further, the GTD wedge diffraction form used is based on the Fresnel integral, so that it is only slightly more complex numerically than knife edge diffraction. Finally, the GTD includes reflections from the sides of the ridge (wedge faces), and can be extended to multiple ridge diffraction and three-dimensional terrain variations.read more
Citations
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Journal ArticleDOI
A survey of various propagation models for mobile communication
TL;DR: An impulse-response characterization for the propagation path is presented, including models for small-scale fading, and it is shown that when two-way communication ports can be defined for a mobile system, it is possible to use reciprocity to focus the energy along the direction of an intended user without any explicit knowledge of the electromagnetic environment in which the system is operating.
Journal ArticleDOI
Site-specific propagation prediction for wireless in-building personal communication system design
TL;DR: Time delay comparison shows that the amplitudes of many significant multipath components are accurately predicted by this model, and the effective building material properties are derived for two dissimilar buildings based upon comparison of measured and predicted power delay profiles.
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Propagation prediction models for wireless communication systems
Magdy F. Iskander,Zhengqing Yun +1 more
TL;DR: A comprehensive review of the propagation prediction models for terrestrial wireless communication systems is presented and the focus is placed on the application of ray-tracing techniques to the development of deterministic propagation models.
Journal ArticleDOI
Survey of channel and radio propagation models for wireless MIMO systems
Peter Almers,Ernst Bonek,Alister G. Burr,Nicolai Czink,Merouane Debbah,Vittorio Degli-Esposti,H. Hofstetter,Pekka Kyosti,David Laurenson,Gerald Matz,Andreas F. Molisch,Claude Oestges,H. Ozcelik +12 more
TL;DR: This paper provides an overview of the state-of-the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO) systems and describes a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models.
References
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Journal ArticleDOI
Geometrical Theory of Diffraction
TL;DR: The mathematical justification of the theory on the basis of electromagnetic theory is described, and the applicability of this theory, or a modification of it, to other branches of physics is explained.
Journal ArticleDOI
A uniform geometrical theory of diffraction for an edge in a perfectly conducting surface
R.G. Kouyoumjian,P.H. Pathak +1 more
TL;DR: In this article, a compact dyadic diffraction coefficient for electromagnetic waves obliquely incident on a curved edse formed by perfectly conducting curved plane surfaces is obtained, which is based on Keller's method of the canonical problem, which in this case is the perfectly conducting wedge illuminated by cylindrical, conical, and spherical waves.
Journal ArticleDOI
High frequency scattering by a thin lossless dielectric slab
Walter D. Burnside,K. Burgener +1 more
TL;DR: In this article, a high frequency solution for scattering from a thin dielectric slab is developed, based on a modification of the uniform geometrical theory of diffraction solution for a haft-plane, with the intention of developing a model for a windshield of a small private aircraft.
Journal ArticleDOI
An evaluation of Longley-Rice and GTD propagation models
K. Chamberlin,R. Luebbers +1 more
TL;DR: In this article, the theory of operation for a terrain-sensitive propagation path loss model based upon the geometrical theory of diffraction, modified for finite conductivity and local surface roughness, is offered.
Journal ArticleDOI
Radio propagation fundamentals
TL;DR: In this article, radio transmission theory and experiment in all frequency bands of current interest are summarized, including ground wave and sky wave transmission, and both line of sight and beyond horizon transmission are considered.
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