Corner-Reflektoren

Corner reflectors are used in the geometric and radiometric calibration and verification of Synthetic Aperture Radar (SAR) sensors as their expected position in a focused SAR image and their expected radar cross section are well-defined through the knowledge of the geodetic position of their phase center (which coincides with the inner corner of the reflector) and their edge length, respectively.
The measurement of the unprecedented localization accuracy of the German TerraSAR-X satellites TSX-1 and TDX-1, which is at the centimeter level, imposes high demands on the knowledge of a corner reflector’s ground position. In order to satisfy these requirements, a test site in the vicinity of an IGS reference station, as it is the case at GARS O’Higgins (see chapter 3.2), allows the position on ground to be measured precisely (< 5 mm) relative to the reference station’s coordinates obtained by terrestrial geodetic survey.
In March 2013, two trihedral 0.7 m corner reflectors were installed at GARS O’Higgins (Fig. 8) within the framework of the HGF Munich Aerospace project “Hochauflösende geodätische Erdbeobachtung” (high resolution geodetic Earth observation). These corner reflectors are part of a network of far-distributed test sites – the other ones are in Wettzell, Germany and in Metsähovi, Finland – whose objective is to evaluate the localization accuracy of the TerraSAR-X mission and to verify the world-wide reproducibility of the obtained measurement results. Thus, the far southern GARS O’Higgins test site plays a key role within the project because of its far distance to the other test sites situated in the Northern Hemisphere.