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Precise Antenna Pointing Determination in Elevation for Spaceborne SAR Systems using Coherent Pattern Differences

Reimann, Jens and Schwerdt, Marco and Schmidt, Kersten and Klenk, Patrick and Steinbrecher, Ulrich and Breit, Helko (2019) Precise Antenna Pointing Determination in Elevation for Spaceborne SAR Systems using Coherent Pattern Differences. Remote Sensing, 11 (3), pp. 320-332. Multidisciplinary Digital Publishing Institute (MDPI). DOI: 10.3390/rs11030320 ISSN 2072-4292

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Official URL: https://www.mdpi.com/2072-4292/11/3/320

Abstract

The precise determination of the SAR antenna pointing is an essential task initially performed during the commissioning phase of a spaceborne SAR system and permanently monitored during the whole mission life time. Besides a correct illumination of the scene during data acquisition, the antenna pointing is required for proper compensation of the radiation pattern for radiometric correction during SAR data processing. The Amazon rainforest is a well-established target area for antenna pointing estimation in elevation as proven by many past and current SAR missions. Several new SAR systems are now proposed which are using long wavelengths, i.e. L- and P-band, which will be implemented using reflector based antenna systems. These reflectors have - in contrast to planar phased array antennas - no completely rigid connection to the satellite body and hence a more volatile antenna pointing. Due to the huge dimensions of such reflector antennas required for the envisaged long wavelengths and the finite stiffness of the boom, the antenna pointing may change significantly along the orbit. Such variation cannot be tracked using the common Amazon rainforest approach only as this measurement opportunity exists only at two positions along the orbit (ascending and descending). Here the performance of an alternative technique is presented which mitigates the influence of the underlying SAR scene by employing two coherent SAR data sets acquired simultaneously with different antenna patterns. This allows the use of amplitude and phase information for pointing estimation. No assumption upon the homogeneity of the underlying scene is required and hence pointing estimation becomes feasible at nearly any point along the orbit. This paper outlines the technique, describes simulation results and presents outcomes from first experimental acquisitions performed with the TerraSAR-X satellite.

Item URL in elib:https://elib.dlr.de/125275/
Document Type:Article
Title:Precise Antenna Pointing Determination in Elevation for Spaceborne SAR Systems using Coherent Pattern Differences
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Reimann, Jensjens.reimann (at) dlr.dehttps://orcid.org/0000-0002-0650-9073
Schwerdt, MarcoMarco.Schwerdt (at) dlr.dehttps://orcid.org/0000-0002-0045-3726
Schmidt, KerstenKersten.Schmidt (at) dlr.dehttps://orcid.org/0000-0001-7896-908X
Klenk, PatrickPatrick.Klenk (at) dlr.deUNSPECIFIED
Steinbrecher, UlrichUlrich.Steinbrecher (at) dlr.deUNSPECIFIED
Breit, HelkoHelko.Breit (at) dlr.dehttps://orcid.org/0000-0001-7865-3288
Date:6 February 2019
Journal or Publication Title:Remote Sensing
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:11
DOI :10.3390/rs11030320
Page Range:pp. 320-332
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
ISSN:2072-4292
Status:Published
Keywords:Synthetic Aperture Radar; Reflector Antenna; Antenna Pointing; Spaceborne SAR; TerraSAR-X; SAR System Calibration; Radiometric Correction; Amazon Rainforest
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Projekt TanDEM-X
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Spaceborne SAR Systems
Remote Sensing Technology Institute > SAR Signal Processing
Deposited By: Reimann, Jens
Deposited On:18 Feb 2019 08:23
Last Modified:19 Feb 2019 09:25

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