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Adaptive Antenna Pattern Notching of Interference in Synthetic Aperture Radar Data Using Digital Beamforming

Bollian, Tobias and Rincon, Rafael and Osmanoglu, Batuhan and Lee, Seung-Kuk and Fatoyinbo, Temilola (2019) Adaptive Antenna Pattern Notching of Interference in Synthetic Aperture Radar Data Using Digital Beamforming. Remote Sensing, 11. Multidisciplinary Digital Publishing Institute (MDPI). DOI: 10.3390/rs11111346 ISSN 2072-4292

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Official URL: https://www.mdpi.com/journal/remotesensing/special_issues/RFI

Abstract

Radio Frequency Interference (RFI) is a growing problem in Synthetic Aperture Radar (SAR) systems as scientific motivations push the radars to lower frequencies and as more wireless services share the frequency spectrum. New, advanced SAR instruments, such as NASA's EcoSAR, DBSAR and DLR's Tandem-L mission, employ a multichannel architecture capable of Digital Beamforming (DBF). Radars with DBF are capable of notching the antenna pattern in specific directions, which can be utilized to suppress RFI on board or in post-processing. A well-researched beamformer for this purpose is the Minimum Variance Distortionless Response (MVDR) Beamformer. However, the number of interferers that can be removed through notching is limited by the number of receive channels. It is therefore essential to adaptively change the antenna pattern notching throughout the image in time and frequency for the best results with a given number of receive channels. In this paper, we present several methods to achieve this notching by making use of the spatial SAR signal distribution in range time, range frequency, azimuth time and azimuth Doppler that is inherent to the SAR imaging geometry. Because this distribution is time-variable and yet predictable, it can be used to improve the angle of arrival estimation of the RFI and the adaptive notching. The presented methods can be applied to a Digital Beamforming (DBF) SAR signal with multiple channels in elevation and/or in azimuth. Simulations show that the proposed methods increase the ability to notch out-of-swath interference from multiple directions and lessen the impact on in-swath interference. The improvement of the interferometric coherence for a single-pass interferogram acquired by NASA's EcoSAR system (capable of DBF in elevation) is demonstrated. The removal of periodic RFI artifacts is achieved.

Item URL in elib:https://elib.dlr.de/127695/
Document Type:Article
Title:Adaptive Antenna Pattern Notching of Interference in Synthetic Aperture Radar Data Using Digital Beamforming
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Bollian, TobiasTobias.Bollian (at) dlr.dehttps://orcid.org/0000-0003-4653-7930
Rincon, Rafaelrafael.rincon (at) nasa.govUNSPECIFIED
Osmanoglu, Batuhanbatuhan.osmanoglu (at) nasa.govUNSPECIFIED
Lee, Seung-Kukseungkuk.lee (at) nasa.govUNSPECIFIED
Fatoyinbo, Temilolalola.fatoyinbo (at) nasa.govUNSPECIFIED
Date:4 June 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/rs11111346
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
ISSN:2072-4292
Status:Published
Keywords:Synthetic Aperture Radar; interference; RFI; digital beamforming; beamformer
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 - Vorhaben Entwicklung eines Mini-SAR
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Radar Concepts
Deposited By: Bollian, Tobias
Deposited On:31 Jul 2019 15:23
Last Modified:20 Dec 2019 17:24

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