Wide-angle azimuth antenna pattern estimation in SAR images

2004 ◽  
Author(s):  
A.M. Guarnieri ◽  
D. D'Aria
Keyword(s):  
Antenna Pattern ◽  
Wide Angle ◽  
Sar Images

Study of Spaceborne Spotlight SAR Coregistration Algorithm

2012 ◽  
Vol 500 ◽  
pp. 368-373
Author(s):  
Xiao Zhen Ren ◽  
Yao Qin ◽  
Hong Liang Fu
Keyword(s):  
Covariance Matrix ◽  
Real Data ◽  
Antenna Pattern ◽  
Sar Interferometry ◽  
Subspace Projection ◽  
Sar Images ◽  
Sample Number ◽  
The Real ◽  
Radar Satellite ◽  
Azimuth Resolution

The azimuth resolution of Spotlight SAR is analyzed from the azimuth antenna pattern weighting, and the effect of the azimuth-varying Doppler on Spotlight SAR interferometry is studied. A coregistration algorithm based on adaptive subspace projection is proposed for Spotlight SAR interferometry. In this method, an adaptive factor is introduced to select the sample number of joint covariance matrix based on the coherence value. Moreover, the Doppler centroid drift in the azimuth direction is also considered in spotlight SAR images coregistration. The method is validated with the real data from the GERMAN radar satellite TerraSAR-X.

scholarly journals METHOD OF AIRBORNE SAR RADIATION CALIBRATION BASED ON POINT TARGET

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 123-128
Author(s):  
S. Yang ◽  
Z. Xu ◽  
C. Cheng
Keyword(s):  
High Precision ◽  
Integral Method ◽  
Calibration Method ◽  
Antenna Pattern ◽  
Sinc Function ◽  
Sar Images ◽  
Key Technology ◽  
Point Target ◽  
Calibration Accuracy ◽  
Airborne Sar

Abstract. Radiation calibration of airborne SAR images is the basis for realizing the quantitative processing of airborne SAR images. Radiation calibration based on point targets is a general and convenient method. However, high precision is still the goal of improving the current point target SAR radiation calibration. For the key technology of high-precision radiation calibration processing for airborne SAR images, this paper uses the integral method and the peak method to calculate the point target radiation response energy, By analysing the radiation characteristics of the SAR image and comparing the methods, the sinc function model is used to fit the corrected antenna pattern. Combined with the radar power equation to solve the calibration constant, the complete point target radiation calibration method and process are established, and the different methods in the key technology are compared and analysed. The results show that the calibration method combined with the energy calculation model of the integral method and the sinc function antenna pattern correction model can achieve higher relative and absolute calibration accuracy. The optimized method can meet and exceed the requirements for radiometric calibration accuracy for high-resolution airborne SAR applications.

scholarly journals First TerraSAR-X TOPS Mode Antenna Pattern Measurements Using Ground Receivers

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Gabriel Castellanos Alfonzo ◽  
Marco Schwerdt ◽  
Steffen Wollstadt ◽  
Markus Bachmann ◽  
Björn Döring ◽  
...  
Keyword(s):  
Antenna Pattern ◽  
Model Verification ◽  
The Novel ◽  
Sar Images ◽  
Flight Direction ◽  
Constant Rate ◽  
Ground Validation ◽  
First Time ◽  
Antenna Model

The antenna model used for correcting the influence of the antenna pattern on synthetic aperture radar (SAR) images requires on-ground validation and in-flight verification. A methodology for the in-flight verification that is based upon the measurement of azimuth antenna patterns using ground receivers has been successfully demonstrated for the operational SAR modes of the TerraSAR-X (TSX) and TanDEM-X (TDX) missions. Recently, the novel (terrain observation by progressive scans) TOPS mode was for the first time implemented as an experimental mode on TerraSAR-X to demonstrate its feasibility in support of its implementation on ESA's Sentinel-1 mission. In this mode, besides scanning in elevation, the antenna beam is steered in flight direction from aft to the front at a constant rate to achieve an enhanced radiometric image performance. This paper discusses the methodology and presents results of the first in-flight antenna characterization of a SAR instrument operating in TOPS mode, in this case TerraSAR-X, using ground receivers. The results demonstrate that the TOPS one-way azimuth antenna pattern can be accurately modeled by the TSX antenna model indicating the general suitability of this approach for the in-flight antenna model verification during TOPS mode operations.

CBED Shadow Images and Cs:Aberration Measurement

1982 ◽  
Vol 40 ◽  
pp. 696-697
Author(s):  
R. W. Carpenter ◽  
I.Y.T. Chan ◽  
J. M. Cowley
Keyword(s):  
Focal Point ◽  
Spherical Aberration ◽  
Optic Axis ◽  
Wide Angle ◽  
Caustic Surface ◽  
Convergent Beam

Wide-angle convergent beam shadow images(CBSI) exhibit several characteristic distortions resulting from spherical aberration. The most prominent is a circle of infinite magnification resulting from rays having equal values of a forming a cross-over on the optic axis at some distance before reaching the paraxial focal point. This distortion is called the tangential circle of infinite magnification; it can be used to align and stigmate a STEM and to determine Cs for the probe forming lens. A second distortion, the radial circle of infinite magnification, results from a cross-over on the lens caustic surface of rays with differing values of ∝a, also before the paraxial focal point of the lens.

Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

1980 ◽  
Vol 38 ◽  
pp. 38-39
Author(s):  
L. T. Germinario ◽  
J. Blackwell ◽  
J. Frank
Keyword(s):  
Protein Complexes ◽  
Hexagonal Lattice ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Insect Cuticle ◽  
High Dose ◽  
Wide Angle ◽  
X Ray ◽  
Averaging Methods ◽  
Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

Developmental Risk Through a Wide-Angle Lens

1987 ◽  
Vol 32 (1) ◽  
pp. 54-55
Author(s):  
Jack P. Shonkoff
Keyword(s):  
Wide Angle ◽  
Developmental Risk ◽  
Wide Angle Lens

Single-peak-regulation and wide-angle dual-band metamaterial absorber based on hollow-cross and solid-cross resonators

2020 ◽  
Vol 91 (3) ◽  
pp. 30901
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Jianming Xu ◽  
Hailang He ◽  
Yuhan Li ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Single Peak ◽  
Wide Angle ◽  
Surface Current Density

A dual-band microwave metamaterial absorber with single-peak regulation and wide-angle absorption has been proposed and illustrated. The designed metamaterial absorber is consisted of hollow-cross resonators, solid-cross resonators, dielectric substrate and metallic background plane. Strong absorption peak coefficients of 99.92% and 99.55% are achieved at 8.42 and 11.31 GHz, respectively, which is basically consistent with the experimental results. Surface current density and changing material properties are employed to illustrate the absorptive mechanism. More importantly, the proposed dual-band metamaterial absorber has the adjustable property of single absorption peak and could operate well at wide incidence angles for both transverse electric (TE) and transverse magnetic (TM) waves. Research results could provide and enrich instructive guidances for realizing a single-peak-regulation and wide-angle dual-band metamaterial absorber.

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