Results 211 to 220 of about 16,272 (256)

The GREGOR polarimetric calibration unit

Astronomische Nachrichten, 2012
AbstractThe new Solar telescope GREGOR is designed to observe small‐scale dynamic magnetic structures below a size of 70 km on the Sun with high spectral resolution and polarimetric accuracy. For this purpose, the polarimetric concept of GREGOR is based on a combination of post‐focus polarimeters with pre‐focus equipment for high precision calibration.
A. Hofmann, K. Arlt, H. Balthasar, S.M. Bauer, W. Bittner, J. Paschke, E. Popow, J. Rendtel, D. Soltau, T. Waldmann   +9 more
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Calibration of polarimetric radar systems

IEEE Antennas and Propagation Society International Symposium 1997. Digest, 2002
The calibration of reciprocal radar systems has been studied previously, where it was shown: (1) that full polarimetric calibration of radar systems can remove cross-polarization errors from the measurements, and (2) that for reciprocal radars Fourier analysis of polarimetric data obtained using a rotating dihedral can reduce the noise and background ...
L.A. Muth, R.C. Wittmann
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Calibration Of Polarimetric Radar Systems

12th Canadian Symposium on Remote Sensing Geoscience and Remote Sensing Symposium,, 2005
A practical technique is proposed for calibrating single-antenna polarimetric radar systems using a metal sphere plus any second target with a strong cross-polarized radar cross section. It is shown that all magnitudes and phases (relative to one of the like-polarized linear polarization configurations) of the radar transfer function can be calibrated ...
K. Sarabandi, F.T. Ulaby
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Calibration of HUT polarimetric radiometer

IGARSS '98. Sensing and Managing the Environment. 1998 IEEE International Geoscience and Remote Sensing. Symposium Proceedings. (Cat. No.98CH36174), 1998
The Helsinki University of Technology polarimetric radiometer calibration system is described. Calibration is based on a metal wire grid polarizer and two absorption loads at different temperatures. The characteristics of the grid and the formulae for calibration are presented. The maximum error due calibration is calculated.
J. Lahtinen, M. Hallikainen
openaire   +1 more source

Polarimetric SAR calibration experiment using active radar calibrators

IEEE Transactions on Geoscience and Remote Sensing, 1990
Active radar calibrators are used to derive both the amplitude and phase characteristics of a multichannel polarimetric synthetic aperture radar (SAR) from the complex image data. Results are presented from an experiment carried out using the NASA/JPL DC-8 aircraft SAR over a calibration site at Goldstone, California.
A. Freeman, Y. Shen, C.L. Werner
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SASAR external polarimetric calibration considerations

IGARSS'97. 1997 IEEE International Geoscience and Remote Sensing Symposium Proceedings. Remote Sensing - A Scientific Vision for Sustainable Development, 2002
SAR polarimetric calibration at frequencies below 150 MHz presents unique challenges when compared to the higher frequency calibration procedures. Low frequency clutter based and point target calibration issues are discussed in this paper.
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A new polarimetric passive radar calibrator for fully polarimetric measurement

Millimetre Wave and Terahertz Sensors and Technology XI, 2018
Conventionally, for the fully polarimetrical calibration of a general non-reciprocal radar system, at least two calibrators such as a dihedral corner reflector plus a sphere are required. A new polarimetric passive radar calibrator for fully polarimetric calibration is proposed in this paper.
Xiaojian Xu, Pengfei Wu
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SIR-C polarimetric calibration by using polarization selective dihedrals and a polarimetric active radar calibrator

IGARSS'97. 1997 IEEE International Geoscience and Remote Sensing Symposium Proceedings. Remote Sensing - A Scientific Vision for Sustainable Development, 2002
A novel approach to calibrate a polarimetric SAR is proposed and tested in the SIR-C/X-SAR experiment. The present technique needs one PARC (polarimetric active radar calibrator) and two PSDs (polarization selective dihedrals). Since PSDs have wide frequency coverage, only addition of another frequency PARC allows to calibrate a multi-frequency ...
M. Fujita, T. Masuda, Y. Fujino, M. Satake   +3 more
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A new polarimetric active radar calibrator and calibration technique

SPIE Proceedings, 2015
Polarimetric active radar calibrator (PARC) is one of the most important calibrators with high radar cross section (RCS) for polarimetry measurement. In this paper, a new double-antenna polarimetric active radar calibrator (DPARC) is proposed, which consists of two rotatable antennas with wideband electromagnetic polarization filters (EMPF) to achieve ...
Jianguo Tang, Xiaojian Xu
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Polarimetric Calibration Using Distributed Clutter

SPIE Proceedings, 1989
Two techniques for using distributed clutter for calibrating a polarimetric radar are given: one uses clutter only but requires knowlege of theoretical clutter polarization ratios; the other requires the use of an in-scene trihedral but requires no foreknowledge of clutter statistics.
openaire   +1 more source