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A calibration concept for passive MW imaging using beam steering by frequency shift and aperture synthesis

Schreiber, Eric and Peichl, Markus and Jirousek, Matthias (2013) A calibration concept for passive MW imaging using beam steering by frequency shift and aperture synthesis. In: Proceedings of SPIE Security + Defence 2013, 8900 (89000E). SPIE Digital Library. SPIE Security + Defence 2013, 23.-26. Sep. 2013, Dresden, Deutschland. doi: 10.1117/12.2028641.

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Official URL: http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1759226


Passive microwave (MW) remote sensing is used in Earth observation missions for example to estimate the salinity of oceans or the soil moisture of landscapes. In these cases the absolute brightness temperature numbers are important for sufficient accuracy of the estimated geo-physical parameters. Consequently a suitable system calibration network is required. At DLR a radiometric demonstrator for fully-electronic MW imaging was set up at Ka band, which is based on a combination of beam steering by frequency shift using a broadband slotted-waveguide antenna for one scanning direction, and the application of aperture synthesis for the other direction. Aperture synthesis is well known from radio astronomy, but it is still a new imaging principle for Earth observation or security applications. Hence as well new calibration techniques have to be developed for this kind of scanning mechanism. In this paper a novel approach for a noise-source based calibration method taking into account the antenna losses will be introduced. When using aperture synthesis techniques to determine the absolute brightness temperature values, it is very important, among other things, to know the exact phase transfer function of the system in order to achieve the desired radiometric resolution. Consequently our approach enables phase calibration as well. The paper outlines a proof of concept for this calibration method using a two-element interferometer called VESAS (Voll Elektronischer Scanner mit AperturSynthese) as a demonstrator. Various calibrated measurement results will be presented and discussed.

Item URL in elib:https://elib.dlr.de/83032/
Document Type:Conference or Workshop Item (Speech)
Title:A calibration concept for passive MW imaging using beam steering by frequency shift and aperture synthesis
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Peichl, MarkusUNSPECIFIEDhttps://orcid.org/0000-0003-0226-9786UNSPECIFIED
Jirousek, MatthiasUNSPECIFIEDhttps://orcid.org/0000-0003-2106-9245UNSPECIFIED
Date:October 2013
Journal or Publication Title:Proceedings of SPIE Security + Defence 2013
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Publisher:SPIE Digital Library
Series Name:Millimetre Wave and Terahertz Sensors and Technology VI
Keywords:Aperture synthesis, frequency dependent scanning, slotted-waveguide antenna, calibration network, noise source, radiometry, microwave imaging, Ka band
Event Title:SPIE Security + Defence 2013
Event Location:Dresden, Deutschland
Event Type:international Conference
Event Dates:23.-26. Sep. 2013
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Security-relevant Earth Observation
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Reconnaissance and Security
Deposited By: Schreiber, Eric
Deposited On:06 Nov 2014 10:31
Last Modified:11 Jul 2023 15:27

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