Wide-Angle Azimuth Antenna Pattern Estimation in SAR Images

We propose a novel technique to estimate the Azimuth Antenna Pattern (AAP) from SAR images. The technique first perform azimuth focusing at enhanced resolution, then selects those scatterers that are less affected by ambiguous returns and finally derive the AAP by spectral analysis. Results achieved by processing ENVISAT-ASAR data are presented

3D vibration estimation from ground-based radar

The paper proposes a method to estimate 2D/3D vibrations and displacements of mostly linear structures, like pipes, chimneys, towers, bridges from afar, based on synchronized Radars. The method takes advantage of Radar sensitivity to displacements to sense tiny deformations (up to tens of micron) with a time scale from milliseconds to hours. The key elements are: (a) The use of calibrators to remove at once both the tropospheric turbulence and the effect of radial motion, and (b) the compensation of interferences from fixed targets. The latter is performed by estimating and removing the contribution of interfering targets, based either on a proper data processing or by exploiting an ad-hoc motorized calibrator. Performance in terms of accuracy of the deformation field is evaluated theoretically and checked by tests carried out in laboratories and by full-scale acquisition campaigns

Phase Requirements, design and validation of phase preserving processor for a spaceborne SAR

The forthcoming generation of SENTINEL-1 SAR demands for high precision phase preserving processors, that would handle the relatively large fractional bandwidth and the extended squint angle span due to TOPSAR. At the same time, efficiency is a must to handle the data rate that comes out from the two polarimetric channels and to cope for fast delivery of products. In this work, we discuss high level requirement on phase noise from interferometric applications and we propose some tests to validate the phase preservation of focusing algorithms in different acquisition geometries

SAR Calibration Aided by Permanent Scatterers

We propose a calibration method suitable for a set of repeated synthetic aperture radar (SAR) acquisitions that uses both absolute calibrated devices (such as corner reflectors) and stable targets identified in the scene [the permanent scatterers (PSs)]. Precisely, the role of the PS is to extend the initial calibration sequence by monitoring the radiometric stability of the system throughout the whole mission life span. At a first step, this paper approaches the problem of PS-based normalization by an iterative maximum-likelihood method that exploits the stack of complex interferometric SAR images. Two solutions are given based on different assumptions on the PS phases. As a second step, the merging of these estimates with the available calibration information is discussed. Results achieved by experimental acquisitions are shown in two different SAR systems: 1) a C-band spaceborne SAR and 2) a Ku-band ground-based SAR