Measurement and analysis of depolarization generated by scattering over constructive obstacles at 5.8 GHz

The interest on the scattering due to constructive obstacles appears in different knowledge areas, mainly radar theory and mobile communications. In radar terms, a target can be identified by means of its scattering pattern. Those patterns are also useful in radio communications, in order to obtain confident models for planning the deployment of networks. If co- polar scattering itself gives an important amount of knowledge, the definition of the obstacle is better done when cross-polar data is incorporated. In order to characterize the scattering patterns due to constructive walls, a measurement campaign has been developed, using an automated system, which integrates the mechanical movement to the vector network analyzer control. The aim of the campaign was to check the reflection behavior of different constructive materials. All the experimental work has been performed at the frequency band around 5.8 GHz. Materials considered are a metallic surface, used as a reference, a brick wall, and a chip wood panel. All sample sizes are large enough to ensure that the 3-dB illuminated area, an ellipse with a major axis of 80 cm, falls within the limits of the slabs, thus reducing any diffraction effects on the edges of the samples. As measurements were performed in co-polar and cross-polar polarizations, both co-polar scattering pattern analysis and depolarization index computations could be made. By means of cross-polar measurements, depolarization indexes can be extracted. This magnitude indicates the percentage of the incident wave that is reflected in the orthogonal polarization. The values obtained for the chip wood panel are between 2 and 3%, and those corresponding to the brick wall are clearly polarization-dependent, being 8% for parallel incidence and 0.4% for perpendicular incidence.