The Experts below are selected from a list of 2649 Experts worldwide ranked by ideXlab platform
Antonio Sarolic - One of the best experts on this subject based on the ideXlab platform.
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RCS simulation and comparison of two shipboard cylindrical trihedral Radar Reflectors in S-band and X-band
2009Co-Authors: Zlatko Zivkovic, Antonio SarolicAbstract:The paper presents the simulation analysis and comparison of two commercially available shipboard cylindrical trihedral Radar Reflectors. The reports found in literature indicate that this type of Radar Reflector provides very poor Radar visibility. Therefore, detailed analysis was carried out taking into account various heeling angles of Radar Reflectors and various azimuth angles of incident plane wave for standard marine navigational Radar frequencies in S-band and X-band. Simulations were performed using FEKO software suite. The simulation results show that the backscatter Radar cross section (RCS) of these Radars is insufficient for reliable performance.
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RCS simulation of a shipboard cylindrical trihedral Radar Reflector in the S-band
2009Co-Authors: Zlatko Zivkovic, Antonio SarolicAbstract:The paper analyzes the Radar cross section (RCS) of a shipboard cylindrical Radar Reflector consisting of vertically stacked rectangular trihedral Reflectors. This kind of Reflector is commonly used on sailboats. However, there have been reports on its low quality regarding Radar visibility, albeit without thorough analysis. The aim of this paper was to simulate its RCS trying to confirm or refute these observations. The simulation was done using Numerical Electromagnetics Code (NEC). The results show that the Radar visibility of this Reflector would be very poor. The RCS declared by the manufacturer cannot be achieved in the S-band, even for the upright vertical position of the Reflector. If the Reflector is heeled (which is always true), its RCS is even smaller, making it practically invisible to a S-band marine Radar in real environment.
Zlatko Zivkovic - One of the best experts on this subject based on the ideXlab platform.
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RCS simulation and comparison of two shipboard cylindrical trihedral Radar Reflectors in S-band and X-band
2009Co-Authors: Zlatko Zivkovic, Antonio SarolicAbstract:The paper presents the simulation analysis and comparison of two commercially available shipboard cylindrical trihedral Radar Reflectors. The reports found in literature indicate that this type of Radar Reflector provides very poor Radar visibility. Therefore, detailed analysis was carried out taking into account various heeling angles of Radar Reflectors and various azimuth angles of incident plane wave for standard marine navigational Radar frequencies in S-band and X-band. Simulations were performed using FEKO software suite. The simulation results show that the backscatter Radar cross section (RCS) of these Radars is insufficient for reliable performance.
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RCS simulation of a shipboard cylindrical trihedral Radar Reflector in the S-band
2009Co-Authors: Zlatko Zivkovic, Antonio SarolicAbstract:The paper analyzes the Radar cross section (RCS) of a shipboard cylindrical Radar Reflector consisting of vertically stacked rectangular trihedral Reflectors. This kind of Reflector is commonly used on sailboats. However, there have been reports on its low quality regarding Radar visibility, albeit without thorough analysis. The aim of this paper was to simulate its RCS trying to confirm or refute these observations. The simulation was done using Numerical Electromagnetics Code (NEC). The results show that the Radar visibility of this Reflector would be very poor. The RCS declared by the manufacturer cannot be achieved in the S-band, even for the upright vertical position of the Reflector. If the Reflector is heeled (which is always true), its RCS is even smaller, making it practically invisible to a S-band marine Radar in real environment.
Takayuki Ono - One of the best experts on this subject based on the ideXlab platform.
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The layered structure of lunar maria: Identification of the HF-Radar Reflector in Mare Serenitatis using multiband optical images
Icarus, 2012Co-Authors: Shoko Oshigami, Shinya Okuno, Yasushi Yamaguchi, Makiko Ohtake, Junichi Haruyama, Takao Kobayashi, Atsushi Kumamoto, Takayuki OnoAbstract:Abstract Comparison of the Lunar Radar Sounder (LRS) data to the Multiband Imager (MI) data is performed to identify the subsurface Reflectors in Mare Serenitatis. The LRS is FM-CW Radar (4–6 MHz) and the 2 MHz bandwidth leads to the range resolution of 75 m in a vacuum, whereas the sampling interval in the flight direction is about 75 m when an altitude of the spacecraft with polar orbit is nominal (100 km). Horizontally continuous Reflectors were clearly detected by LRS in limited areas that consist of about 9% of the whole maria. The typical depth of the Reflectors is estimated to be a few hundred meters. Layered structures of mare basalts are also discernible on some crater walls in the MI data of the visible bands (VIS). The VIS range has nine wavelengths of 415, 750, 900, 950, and 1000 nm, and their spatial resolution is 20 m/pixel at a nominal altitude. The stratigraphies around Bessel and Bessel-H craters in Mare Serenitatis are examined in this paper. It was revealed that the subsurface Reflectors lie on the boundaries between basalt units with different chemical compositions. In addition, model calculations using the simplified Radar equation indicate that the subsurface Reflectors are not compositional interfaces but layer boundaries with a high-porosity contrast. These results suggest that the detected Reflectors in Mare Serenitatis are regolith accumulated during so long hiatus of mare volcanisms enough for chemical composition of magma to change, not instantaneously. Therefore combination of the LRS and MI data has a potential to reveal characteristics of a series of magmatism forming each lithostratigraphic unit in Mare Serenitatis and other maria.
Kathryn E. Fishbaugh - One of the best experts on this subject based on the ideXlab platform.
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Integrating Radar stratigraphy with high resolution visible stratigraphy of the north polar layered deposits, Mars
Icarus, 2013Co-Authors: S. Christian, John W. Holt, Shane Byrne, Kathryn E. FishbaughAbstract:Abstract Shallow Radar (SHARAD) on board NASA’s Mars Reconnaissance Orbiter has successfully detected tens of Reflectors in the subsurface of the north polar layered deposits (NPLD) of Mars. Radar reflections are hypothesized to originate from the same material interfaces that result in visible layering. As a first step towards verifying this assumption, this study uses signal analyses and geometric comparisons to quantitatively examine the relationship between Reflectors and visible layers exposed in an NPLD outcrop. To understand subsurface structures and Reflector geometry, Reflector surfaces have been gridded in three dimensions, taking into account the influence of surface slopes to obtain accurate subsurface geometries. These geometries reveal Reflector dips that are consistent with optical layer slopes. Distance–elevation profiling of subsurface Reflectors and visible layer boundaries reveals that Reflectors and layers demonstrate similar topography, verifying that Reflectors represent paleosurfaces of the deposit. Statistical and frequency-domain analyses of the separation distances between successive layers and successive Reflectors confirms the agreement of Radar Reflector spacing with characteristic spacing of certain visible layers. Direct elevation comparisons between individual Reflectors and discrete optical layers, while necessary for a one-to-one correlation, are complicated by variations in subsurface structure that exist between the outcrop and the SHARAD observations, as inferred from subsurface mapping. Although these complications have prevented a unique correlation, a genetic link between Radar Reflectors and visible layers has been confirmed, validating the assumption that Radar Reflectors can be used as geometric proxies for visible stratigraphy. Furthermore, the techniques for conducting a stratigraphic integration have been generalized and improved so that the integration can be undertaken at additional locations.
Shoko Oshigami - One of the best experts on this subject based on the ideXlab platform.
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The layered structure of lunar maria: Identification of the HF-Radar Reflector in Mare Serenitatis using multiband optical images
Icarus, 2012Co-Authors: Shoko Oshigami, Shinya Okuno, Yasushi Yamaguchi, Makiko Ohtake, Junichi Haruyama, Takao Kobayashi, Atsushi Kumamoto, Takayuki OnoAbstract:Abstract Comparison of the Lunar Radar Sounder (LRS) data to the Multiband Imager (MI) data is performed to identify the subsurface Reflectors in Mare Serenitatis. The LRS is FM-CW Radar (4–6 MHz) and the 2 MHz bandwidth leads to the range resolution of 75 m in a vacuum, whereas the sampling interval in the flight direction is about 75 m when an altitude of the spacecraft with polar orbit is nominal (100 km). Horizontally continuous Reflectors were clearly detected by LRS in limited areas that consist of about 9% of the whole maria. The typical depth of the Reflectors is estimated to be a few hundred meters. Layered structures of mare basalts are also discernible on some crater walls in the MI data of the visible bands (VIS). The VIS range has nine wavelengths of 415, 750, 900, 950, and 1000 nm, and their spatial resolution is 20 m/pixel at a nominal altitude. The stratigraphies around Bessel and Bessel-H craters in Mare Serenitatis are examined in this paper. It was revealed that the subsurface Reflectors lie on the boundaries between basalt units with different chemical compositions. In addition, model calculations using the simplified Radar equation indicate that the subsurface Reflectors are not compositional interfaces but layer boundaries with a high-porosity contrast. These results suggest that the detected Reflectors in Mare Serenitatis are regolith accumulated during so long hiatus of mare volcanisms enough for chemical composition of magma to change, not instantaneously. Therefore combination of the LRS and MI data has a potential to reveal characteristics of a series of magmatism forming each lithostratigraphic unit in Mare Serenitatis and other maria.