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Handbook of Antenna Technologies – Chapter Radiometer Antennas

Peichl, Markus (2016) Handbook of Antenna Technologies – Chapter Radiometer Antennas. In: Handbook of Antenna Technologies Springer Reference. Springer Science+Business Media Singapore. Seiten 2727-2794. doi: 10.1007/978-981-4560-44-3. ISBN 978-981-4560-43-6.

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Offizielle URL: http://link.springer.com/book/10.1007%2F978-981-4560-44-3

Kurzfassung

Microwave radiometry is concerned with purely passive sensing of naturally generated microwave radiation of thermal origin. Microwave radiometers are corresponding measuring devices typically designed and built as a very low-noise receiver followed by a signal recording unit. Usually, radiometers contain an antenna as the first reception component collecting the incoming radiation, and they measure radiation power expressed in an apparent temperature called brightness temperature. The observable brightness temperature of any object or surface depends on various chemical and physical quantities, whose concurrence is expressed by the objects’ emission (absorption), reflection, and transmission properties and its true temperature. Since the Earth has a temperature typically close to 300 K and the universe close to 3 K, a nearly arbitrary mixture of these two extreme temperatures can be expected. Consequently, our environment can show quite different brightness temperature values depending on the direction of actual observation. On the one hand, radiometer measurements are carried out stationary with respect to the antenna pointing direction in order to observe time-dependent variations of the brightness temperature. On the other hand, the brightness temperature of a whole scene is scanned in order to acquire locally changing one- or two-dimensional profiles, while the latter ones are assembled as a two-dimensional image comparable to a conventional photograph. Depending on the specific application, various antenna types are considered, where usually hard requirements with respect to beam width, side-lobe level, scan capability, and losses have to be addressed (▶Transmission Lines). Radiometric measurements are performed for Earth or planetary observation in space (▶Space Antennas including Terahertz Antennas), from aircraft platforms on the Earth’s surface and the atmosphere, or on the ground, either sensing the environment or sensing the universe, the latter being performed in radio astronomy (▶Antennas in Radio Telescope Systems). Usually, the brightness temperature is rarely used as the physical quantity of interest. More often, it is transferred via adequate physical models to other secondary or third quantities for more direct use in the case of Earth observation (e.g., soil moisture, ocean salinity, rain rate, snow cover, etc.), being performed already since the 1950s of the last century. However, in the last decades, microwave radiometry is as well used in many safety- and security-related applications, for which often only sufficient temperature contrast between an object and its surrounding is required besides spatial resolution for detection and recognition purposes. In this chapter relevant fundamentals of microwave radiometry are outlined for better understanding of antenna requirements, followed by an overview of typical types of radiometer antenna systems. Some existing antenna systems are discussed in order to illustrate the variability with respect to applications. A section on basic antenna quantities addresses key figures for practical design and verification and illustrates the results exemplarily for selected cases. Finally, a brief summary and an outlook on possible future implementations and other frequency ranges are given.

elib-URL des Eintrags:https://elib.dlr.de/110638/
Dokumentart:Beitrag in einem Lehr- oder Fachbuch
Titel:Handbook of Antenna Technologies – Chapter Radiometer Antennas
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Peichl, MarkusMarkus.Peichl (at) dlr.dehttps://orcid.org/0000-0003-0226-9786NICHT SPEZIFIZIERT
Datum:2016
Erschienen in:Handbook of Antenna Technologies
Referierte Publikation:Nein
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
DOI:10.1007/978-981-4560-44-3
Seitenbereich:Seiten 2727-2794
Herausgeber:
HerausgeberInstitution und/oder E-Mail-Adresse der HerausgeberHerausgeber-ORCID-iDORCID Put Code
Chen, Z.N.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Liu, D.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Nakano, H.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Qing, X.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Zwick, T.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Verlag:Springer Science+Business Media Singapore
Name der Reihe:Springer Reference
ISBN:978-981-4560-43-6
Status:veröffentlicht
Stichwörter:Microwave radiometry; Earth observation; Security; Antenna temperature; Antenna losses; Antenna reflection; Mechanical scanner; Focal plane array; Aperture synthesis; Frequency scanning; Digital beamforming; Sparse array; Spatial resolution; Sensitivity; Sampling
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Raumfahrt
HGF - Programmthema:Erdbeobachtung
DLR - Schwerpunkt:Raumfahrt
DLR - Forschungsgebiet:R EO - Erdbeobachtung
DLR - Teilgebiet (Projekt, Vorhaben):R - Sicherheitsrelevante Erdbeobachtung
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Hochfrequenztechnik und Radarsysteme > Aufklärung und Sicherheit
Hinterlegt von: Peichl, Dr.-Ing. Markus
Hinterlegt am:12 Jan 2017 15:36
Letzte Änderung:22 Nov 2019 08:33

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