F. Pérez Fontán

Attenuation of Spruce, Pine, and Deciduous Woodland at C-Band

The presence of vegetation in the radio path significantly attenuates centimeter and millimeter radio waves. The attenuation depends on the type of vegetation, its density, the season, and the frequency. Attenuation models exist for the horizontal path through vegetation and the slant foliage path through roadside trees. In this study, slant foliage paths through roadside woodland are investigated. This letter presents results for the slant path attenuation loss at 5.2-GHz C-band frequency at three elevation angles (20°, 40°, and 60°) and three types of vegetation (spruce, pine, and deciduous woodland). Differences between horizontal and slant path results are discussed, and cumulative distribution statistics of the attenuation in the various vegetation types are given.

A methodology for the characterization of environmental effects on global navigation satellite system (GNSS) propagation

In this paper a methodology for the characterization of environment-related (shadowing and multipath) propagation effects on multi-satellite systems is presented. This work is focused on availability and performance evaluation of global navigation satellite systems (GNSSs). The definition of next-generation GNSSs specially designed for civil applications requires the precise understanding of propagation effects; these include not only ionospheric and tropospheric but also environmental effects, since a large group of their expected users will no longer be located in open areas with clear visibility of several satellites but in densely built-up areas subject to high blockage probabilities. Issues such as constellation definition, signal design, codeword structure, etc. require the aid of powerful analysis tools. The basic ideas for the specification of such multi-satellite propagation analysis tools are presented. This paper describes part of the work being carried out under European Space Agency (ESA) contract ESA/ESTEC 12223/96/NL/JSC.

Radar Rain Cell Identification and Modeling in the North-West of Spain

This study aims to characterize and model the rain fields in the North-West of Spain from Weather Radar Images. The study includes the modeling of these images according to two well known rain cell models: EXCELL and HYCELL. For this analysis, a procedure to detect rain fields and an algorithm for identifying rain cells within the images is presented. This work is part of an on-going activity trying to develop dynamic space-time models for rain fields for simulating rain induced effects on millimeter wave communication systems.