Tandem-L is a highly innovative SAR satellite mission for the global observation of dynamic processes on the Earth's surface with hitherto unknown quality and resolution. Thanks to its novel imaging techniques and its unprecedented acquisition capacity, Tandem-L will deliver urgently needed information for the solution of pressing scientific questions in the areas of the biosphere, geosphere, cryosphere and hydrosphere. The feasibility of Tandem-L has been analyzed and confirmed in the scope of a phase A study, which has been conducted in close cooperation between the German Aerospace Center (DLR) and the German space industry. This paper provides an overview of the Tandem-L mission concept and summarizes the actual development status.

This paper presents a novel concept of a spaceborne Digital Beamforming (DBF) Synthetic Aperture Radar (SAR) based on a multi-beam reflectarray antenna. The proposed solution offers a number of advantages compared to more conventional DBF SAR systems using planar arrays or reflector antennas. The paper focuses on the spaceborne DBF SAR and discusses its architecture, system parameters and an imaging scenario. A reflectarray antenna design to be used in a combination with the considered imaging platform is presented in the paper. The reflectarray model is used to estimate DBF SAR performance characteristics discussed in the final part of the paper.

This paper describes the performance analysis of a Ka-band Synthetic Aperture Radar (SAR) system working in joint mode, which is able to provide an adequate Cross-Track Interferometric (XTI) and Ground Moving Target Indication (GMTI) performance. The common major problem of joint mode is the low Pulse Repetition Frequency (PRF). To overcome this problem a long receive antenna is considered, which allows a reduction of the PRF, resulting in an increase of the swath widths. The receive antenna is constituted by nine equal reflectarray modules and the transmit antenna consists of two reflectarray modules, both antennas are able to work in narrow and wide swath modes.

This paper presents two reflectarray antenna configurations used as receive and transmit antennas for a ku-band Synthetic Aperture Radar system (SAR). The receive antenna is constituted by nine equal single offset reflectarray modules. The transmit antenna is based in two dual offset parabolic reflector antenna with a rectangular reflectarray as main reflector. Both receive and transmit antennas are able to work in two different modes using orthogonal polarizations, the narrow swath mode and wide swath mode.

This paper presents a novel concept of a spaceborne Digital Beamforming (DBF) Synthetic Aperture Radar (SAR) based on a multi-beam reflectarray antenna. The proposed solution offers a number of advantages compared to more conventional DBF SAR systems using planar arrays or reflector antennas. The paper focuses on the spaceborne DBF SAR architecture using a reflectarray antenna designed for the imaging platform. DBF SAR system parameters, an imaging scenario and a reflectarray antenna model are described in detail. The results of a performance analysis of the SAR system are presented and discussed in the paper.