Polarization Capabilities and Status of TERRASAR-X
Irena Hajnsek(1), Josef Mittermayer(1) and Kostas Papathanassiou(1)
(1) German Aerospace Center, PO BOX 1116, 82234, Germany
TerraSAR-X is the first German Radar satellite for scientific and commercial applications. The project is a public-private partnership between DLR and EADS Astrium GmbH. TerraSAR-X consists of a high resolution Synthetic Aperture Radar at X-Band. The radar antenna is based on active phased array technology that allows the control of many different instrument parameters and operational modes (Stripmap, ScanSAR and Spotlight) with various polarizations. The TerraSAR-X launch was the 15 June 2007. Only 4 days later the first image was delivered.
The variety of TerraSAR-X polarization modes is reviewed and validation results of each mode are presented. The polarization modes include operational modes like dual-pol in Stripmap and Spotlight. Additionally there are experimental modes like twin polarization mode which is similar to the ASAR alternating polarization mode, or the full polarimetric mode which is realized in the TerraSAR-X Dual Receive Antenna configuration.
The Dual Receiving Antenna Mode (DRA) of TerraSAR-X offers a high variety of interesting applications and experiments, e.g. along track interferometry, geometric resolution enhancement and especially the full polarimetric mode. In the DRA mode of TerraSAR-X, the complete antenna is used for transmission but in receive, the antenna is divided into two separate partitions in along track. The signals of both receiving antennas are recorded separately by exploiting the redundant receiver chain of the instrument. Both signals are not recorded separately but as sum and difference signal. This demands for special calibration in the reconstruction of fore and aft channel before SAR processing and has influence on the polarimetric performance.
The paper provides a selection of TS-X images acquired in different polarization modes and thus demonstrates the polarimetric capabilities of TerraSAR-X.