SAR/GMTI for Space-Based Radar with Two-Dimensional Antenna Arrays

Abstract

Synthetic Aperture Radar / Ground Moving Target Indication (SAR / GMTI) is an active radar remote sensing technique, based on the coherent combination of SAR imaging and antenna array processing. The SAR / GMTI technique provided a step forward in quantitative ground motion parameter estimation. In the last two decades, airborne SAR / GMTI experiments, and in the last years also spaceborne SAR / GMTI experiments evaluated the potential of the SAR / GMTI techniques to estimate ground motion parameters (i.e. target position, velocity, and motion direction). This dissertation addresses the actual status, the potentials and limitations of spaceborne SAR / GMTI with single / monostatic platforms carrying two-dimensional antenna arrays. The SAR processing is applied in order to generate high resolution images of the target signals, antenna array processing in along-track direction is applied for GMTI and antenna array processing in across-track direction in order to cover large swathes. This trade-off between SAR imaging capability, GMTI capability and swath coverage requires a careful design of radar systems and operation modes. Therefore, one main goal of this dissertation is to provide new spaceborne radar system designs and operation modes which provide a good trade-off between GMTI capability and swath coverage, and furthermore a high flexibility in adjusting between SAR capability and GMTI capability. One considered future SAR system is Astrium’s High Resolution Wide Swath Reference System. Another system is a radar design which is characterized mainly by a largely increased beamsteering capability. Besides, one secondary objective of this dissertation were to extend the signal modeling for combining SAR imaging and antenna array processing in spaceborne geometries. Another secondary objective was to calibrate the first available spaceborne SAR / along-track array experimental data, namely the data from the TerraSAR-X dual receive antenna mode. Lastbut not least, another secondary objective of this dissertation was to demonstrate the validity of the signal and performance modeling by processing the data from airborne and spaceborne experimental campaigns.