Figure 4

Extent of reflective surfaces. The reflection areas were approximated by the first Fresnel zone for an antenna at height 4.3 m over the reflective surface. The contours describe the reflective surfaces, for GPS observations at frequency L₁ and for elevation angles 5° (magenta dashed-line), 15° (cyan solid line), 30° (green dashed line), and 50° (blue solid line). The corresponding areas are 338, 38, 10, and 4 m², respectively. The GPS antenna is represented as a left-pointing triangle, located in the origin, and the specular point for each surface is marked with a plus sign.