A method to generate several phase centres on a single parabolic reflector antenna fed by a digital beamforming array is presented. Among other applications, along-track SAR interferometry at higher frequencies, as for example, in the Ka-band, is considered. Flexibility in size, position and amount of phase centres is similar as for a setup using a direct radiating array.

In this paper different experiments conducted with the TerraSAR-X satellite for a demonstration of digital beamforming in elevation are shown for a spaceborne SAR system. Processing of the data and different options for digital beamforming are presented.

In this paper the flexibility in modifying the resulting antenna characteristics in terms of location of phase centres and aperture widths, independent of the antenna type used by applying linear combinations of digital beams is discussed. Especially a parabolic reflector can be considered to have the same properties as a Direct Radiating Array (DRA) when used for SAR applications like along-track interferometry.

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.

A transmit scheme that uses several timed and directed sub-pulses to cover one common swath is proposed. Timing and ambiguity suppression is presented. The advantages of the proposed scheme are an increased sensitivity compared to one transmit pulse per swath and a simpler activation scheme of the receivers in combination with lower data compression effort on-board a satellite.

In the general effort of understanding climate change, one of the key challenges is understanding the feedback loops between the global climate system and the Cryosphere. Current observations qualitatively show that the Cryosphere reacts very sensitively to climate change. However, improved observation capabilities are needed in order to better quantify some of the observed processes. In particular, in order to quantify the complex dynamics of ice mass balances, a detailed and accurate knowledge of the time varying ice surface topography is needed.

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.