The Experts below are selected from a list of 6462 Experts worldwide ranked by ideXlab platform
D.e. Lawrence - One of the best experts on this subject based on the ideXlab platform.
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acoustic and electromagnetic wave interaction estimation of Doppler Spectrum from an acoustically vibrated metallic circular cylinder
IEEE Transactions on Antennas and Propagation, 2003Co-Authors: K. Sarabandi, D.e. LawrenceAbstract:The idea of using acoustically induced Doppler spectra as a means of target detection and identification is introduced. An analytical solution for the calculation of the bistatic scattered Doppler Spectrum from an acoustically excited, vibrating, metallic, circular cylinder is presented. First, the electromagnetic scattering solution of a slightly deformed circular cylinder is obtained using a perturbation method. Then, assuming the vibration frequency is much smaller than the frequency of the incident electromagnetic wave, a closed form expression for the time-frequency response of the bistatic scattered field is obtained which can be used directly for estimating the Doppler Spectrum. The acoustic scattering solution for an incident acoustic plane wave upon a solid elastic cylinder is applied to give the displacement of the cylinder surface as a function of time. Results indicate that the scattered Doppler frequencies correspond to the mechanical vibration frequencies of the cylinder, and the sidelobe Doppler Spectrum level is, to the first order, linearly proportional to the degree of deformation and is a function of bistatic angle. Moreover, the deformation in the cylinder, and thus the Doppler sidelobe level, only becomes sizeable near frequencies of normal modes of free vibration in the cylinder. Utilizing the information in the scattered Doppler Spectrum could provide an effective means of buried object identification, where acoustic waves are used to excite the mechanical resonances of a buried object.
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Estimation of Doppler Spectrum from a vibrating metallic circular cylinder
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC URSI National Radio Science Meeting (Cat. N, 1999Co-Authors: K. Sarabandi, D.e. LawrenceAbstract:An analytical solution for the calculation of the bistatic scattered Doppler Spectrum from a vibrating metallic circular cylinder is presented. First the scattering solution of a slightly deformed circular cylinder is obtained using a perturbation method. Then, assuming the vibration frequency is much smaller than the frequency of the incident electromagnetic plane wave, a closed form expression for the time-frequency response of the bistatic scattered field is obtained which can be used directly for estimating the Doppler Spectrum. Results indicate that the scattered Doppler frequencies correspond to the mechanical vibration frequencies of the cylinder, and the sidelobe Doppler Spectrum level is, to the first order, linearly proportional to the degree of deformation and is a function of bistatic angle. Utilizing the information in the scattered Doppler Spectrum could provide an effective means of buried object identification, where acoustic waves are used to vibrate the buried object at resonance.
E M Meshkov - One of the best experts on this subject based on the ideXlab platform.
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Application of Doppler Spectrum for Retrieval of Statistical Parameters of Sea Waves
2nd European Conference on Antennas and Propagation (EuCAP 2007), 2020Co-Authors: V.yu. Karaev, M. B. Kanevsky, E M MeshkovAbstract:The experiment for studying of microwave backscatter by the rough water surface during the flight above the Gorky water storage basin was performed. A Doppler radar (10GHz) with a knife-like beam (1° - 16°) was installed at a helicopter and was oriented vertically downward. The analysis of the experimental data has confirmed that the width of the Doppler Spectrum depends on the direction of wave propagation. The new algorithm for determination the correlation coefficient between the vertical component of the orbital velocity and water surface slopes, as well as the variance of orbital velocity was developed using the width of the Doppler Spectrum of the reflected radar signal for the case of moving radar. The experimental data processing has confirmed the effectiveness of retrieval algorithm and demonstrated the possibility to determine the average phase velocity of sea waves, the average wavelength, and the significant wave height. (6 pages)
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The Doppler Spectrum of The Microwave Radar Signal Backscattered by the Sea Surface at Low Incidence Angles
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Vladimir Karaev, Mariya Ryabkova, M A Panfilova, Yury Titchenko, E M MeshkovAbstract:Results of the first experiment on measuring the Doppler Spectrum of the microwave signal backscattered by the sea surface at low incidence angles (
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the Doppler Spectrum of the microwave radar signal backscattered by the sea surface at low incidence angles
International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Vladimir Karaev, Mariya Ryabkova, M A Panfilova, Yury Titchenko, E M MeshkovAbstract:Results of the first experiment on measuring the Doppler Spectrum of the microwave signal backscattered by the sea surface at low incidence angles (< 20°) made from a sea platform are presented. At small incidence angles (<10°), the reflection is quasi-specular and the Kirchhoff approximation is used to calculate the Doppler Spectrum. Comparison showed a good agreement between the experiment and numerical estimates of the Doppler Spectrum model. The measurements have shown that in the transition range of incidence angles (10°-20°), one should take into account the resonant scattering contribution to explain the features of the measured Doppler Spectrum. To calculate the Doppler Spectrum in the transition range, an advanced Bragg scattering model was used. It is shown that the employed quasi-specular and Bragg scattering mechanisms qualitatively explain the dependences of the width and shift of the Doppler Spectrum on the incidence angle. In passing to quantitative estimates, tilt modulation and hydrodynamic modulation of the Bragg scattering mechanism should be taken into account, which will be done in a future study. The first measurements of the dependences of the width and shift of the Doppler Spectrum on the incidence angle allow comparing well-known scattering models.
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IGARSS - The Doppler Spectrum of The Microwave Radar Signal Backscattered by the Sea Surface at Low Incidence Angles
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Vladimir Karaev, Mariya Ryabkova, M A Panfilova, Yury Titchenko, E M MeshkovAbstract:Results of the first experiment on measuring the Doppler Spectrum of the microwave signal backscattered by the sea surface at low incidence angles (< 20°) made from a sea platform are presented. At small incidence angles (
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the effect of sea surface slicks on the Doppler Spectrum width of a backscattered microwave signal
Sensors, 2008Co-Authors: Vladimir Karaev, M. B. Kanevsky, E M MeshkovAbstract:The influence of a surface-active substance (SAS) film on the Doppler Spectrum width at small incidence angles is theoretically investigated for the first time for microwave radars with narrow-beam and knife-beam antenna patterns. It is shown that the requirements specified for the antenna system depend on the radar motion velocity. A narrow-beam antenna pattern should be used to detect slicks by an immobile radar, whereas radar with a knife-beam antenna pattern is needed for diagnostics from a moving platform. The study has revealed that the slick contrast in the Doppler Spectrum width increases as the radar wavelength diminishes, thus it is preferable to utilize wavelengths not larger than 2 cm for solving diagnostic problems. The contrast in the Doppler Spectrum width is generally weaker than that in the radar backscattering cross section; however, spatial and temporal fluctuations of the Doppler Spectrum width are much weaker than those of the reflected signal power. This enables one to consider the Doppler Spectrum as a promising indicator of slicks on water surface.
K. Sarabandi - One of the best experts on this subject based on the ideXlab platform.
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Millimeter wave RCS and Doppler Spectrum of walking human and dog
2007 IEEE Antennas and Propagation Society International Symposium, 2007Co-Authors: M. Vahidpour, K. SarabandiAbstract:This paper presents a polarimetric model for backscatter and its Doppler Spectrum of a walking human and a dog subject at W-band using GO-PO method. Polarimetric measurements of human target with and without a firearm are also presented to demonstrate the increase in the level of cross-polarized backscatter. Furthermore, we present a time-frequency analysis to separate polarimetric response of the human torso.
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acoustic and electromagnetic wave interaction estimation of Doppler Spectrum from an acoustically vibrated metallic circular cylinder
IEEE Transactions on Antennas and Propagation, 2003Co-Authors: K. Sarabandi, D.e. LawrenceAbstract:The idea of using acoustically induced Doppler spectra as a means of target detection and identification is introduced. An analytical solution for the calculation of the bistatic scattered Doppler Spectrum from an acoustically excited, vibrating, metallic, circular cylinder is presented. First, the electromagnetic scattering solution of a slightly deformed circular cylinder is obtained using a perturbation method. Then, assuming the vibration frequency is much smaller than the frequency of the incident electromagnetic wave, a closed form expression for the time-frequency response of the bistatic scattered field is obtained which can be used directly for estimating the Doppler Spectrum. The acoustic scattering solution for an incident acoustic plane wave upon a solid elastic cylinder is applied to give the displacement of the cylinder surface as a function of time. Results indicate that the scattered Doppler frequencies correspond to the mechanical vibration frequencies of the cylinder, and the sidelobe Doppler Spectrum level is, to the first order, linearly proportional to the degree of deformation and is a function of bistatic angle. Moreover, the deformation in the cylinder, and thus the Doppler sidelobe level, only becomes sizeable near frequencies of normal modes of free vibration in the cylinder. Utilizing the information in the scattered Doppler Spectrum could provide an effective means of buried object identification, where acoustic waves are used to excite the mechanical resonances of a buried object.
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Estimation of Doppler Spectrum from a vibrating metallic circular cylinder
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC URSI National Radio Science Meeting (Cat. N, 1999Co-Authors: K. Sarabandi, D.e. LawrenceAbstract:An analytical solution for the calculation of the bistatic scattered Doppler Spectrum from a vibrating metallic circular cylinder is presented. First the scattering solution of a slightly deformed circular cylinder is obtained using a perturbation method. Then, assuming the vibration frequency is much smaller than the frequency of the incident electromagnetic plane wave, a closed form expression for the time-frequency response of the bistatic scattered field is obtained which can be used directly for estimating the Doppler Spectrum. Results indicate that the scattered Doppler frequencies correspond to the mechanical vibration frequencies of the cylinder, and the sidelobe Doppler Spectrum level is, to the first order, linearly proportional to the degree of deformation and is a function of bistatic angle. Utilizing the information in the scattered Doppler Spectrum could provide an effective means of buried object identification, where acoustic waves are used to vibrate the buried object at resonance.
Y. Zhao - One of the best experts on this subject based on the ideXlab platform.
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A Stuty of Doppler Spectrum from Time-Varying Sea with a Low-Flying Small Target Above It
2018 IEEE International Conference on Computational Electromagnetics (ICCEM), 2018Co-Authors: Pengju Yang, R. Wu, Y. Q. Zhang, Y. Zhao, Wei TianAbstract:In order to fast and accurately calculate the composite scattering from time-varying sea surfaces with a Low-flying small target above it, a hybrid algorithm of Kirchhoff approximation (KA) and method method-of-moments (MoM) is utilized in this paper for analyzing the Doppler Spectrum signatures of Low-flying small target located above rough sea surfaces. The effect of sea state parameters, incidence angles, the speed of flying target, the distance between the target and the sea surfaces, the shape of the target' cross-section on Doppler Spectrum signatures of a low-flying small target above time-varying sea surface is investigated in detail in this paper.
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Doppler Spectrum of Backscattered Field from Time-Varying Sea with a Low-Flying Small Target Above It
2018 12th International Symposium on Antennas Propagation and EM Theory (ISAPE), 2018Co-Authors: P. J. Yang, J. Kang, R. Wu, Y. Q. Zhang, Y. Zhao, Y. Q. WangAbstract:In this paper, the Doppler Spectrum of backscattered echoes from moving target above time-varying sea surfaces is investigated by utilizing the quasi-stationary algorithm, i.e., approximating the time-domain problem by repeatedly implementing the frequency-domain method. In order to fast and accurately solve the composite scattering problem of time-varying sea surfaces with a Low-flying small target above it, a hybrid algorithm of Kirchhoff approximation (KA) and method method-of-moments (MoM) is utilized in this paper for analyzing the Doppler Spectrum signatures. The effect of the speed of flying target on Doppler Spectrum signatures of a low-flying small target above time-varying sea surface is investigated in this paper.
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Radar Scattering From the Composite Ship-Ocean Scene: Doppler Spectrum Analysis Based on the Motion of Six Degrees of Freedom
IEEE Transactions on Antennas and Propagation, 2014Co-Authors: Y. Zhao, Min Zhang, Hui Chen, Xiao-feng YuanAbstract:In general, a ship moves with translation and rotation under the action of water. The investigation of the motion of ship is useful for the scattering echo simulation. In this communication, we firstly focus on modeling and simulation for the motion of ship in six degrees of freedom in two dimensional (2-D) sea surface based on the program public domain strip method (PDSTRIP). Then, some further simulations and the influence of various parameters (such as the polarization, incident angle and wind direction) on the Doppler Spectrum are analyzed to prove that the facet-based asymptotical model is an effective model to investigate the EM scattering from the 2-D sea surface. Finally, in consideration of the motion of ship in six degrees of freedom, the radar echo and Doppler Spectrum of the dynamic composite maritime scene are then studied based on the proposed specular reflection weighted four-path model. It is found that the motion of ship has the most significant effect on the RCS and Doppler Spectrum.
Vladimir Karaev - One of the best experts on this subject based on the ideXlab platform.
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Doppler Spectrum of Microwaves at Forward Scattering from the Sea Surface
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Yuriy Titchenko, Vladimir KaraevAbstract:The work is aimed at developing a new approach to bistatic remote sensing of the sea surface. The basis of the new approach is the analysis of the shape of the Doppler Spectrum of the signal reflected in the forward direction from the sea surface. The Doppler Spectrum contains more information about the reflecting surface than the scattering cross section, since the cross section is an integral characteristic of the Doppler Spectrum. The advantage of the Doppler Spectrum is also its greater versatility when comparing the measurements of various instruments comparing to the scattering cross section. The paper presents the final expressions for the width and shift of the Doppler Spectrum of microwaves reflected by the sea surface during bistatic sensing in the case of a moving receiver and a transmitter. An important feature of the proposed approach is the consideration of the antennas patterns of the receiving and transmitting antennas. And it is taken into account that the antennas patterns of the receiver and transmitter can be different and asymmetrical. The correct choice and use of antennas with different patterns allows directly expressing the sea surface parameters of interest from the measured characteristics of the Doppler Spectrum.
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The Doppler Spectrum of The Microwave Radar Signal Backscattered by the Sea Surface at Low Incidence Angles
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Vladimir Karaev, Mariya Ryabkova, M A Panfilova, Yury Titchenko, E M MeshkovAbstract:Results of the first experiment on measuring the Doppler Spectrum of the microwave signal backscattered by the sea surface at low incidence angles (
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IGARSS - Doppler Spectrum of Microwaves at Forward Scattering from the Sea Surface
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Yuriy Titchenko, Vladimir KaraevAbstract:The work is aimed at developing a new approach to bistatic remote sensing of the sea surface. The basis of the new approach is the analysis of the shape of the Doppler Spectrum of the signal reflected in the forward direction from the sea surface. The Doppler Spectrum contains more information about the reflecting surface than the scattering cross section, since the cross section is an integral characteristic of the Doppler Spectrum. The advantage of the Doppler Spectrum is also its greater versatility when comparing the measurements of various instruments comparing to the scattering cross section. The paper presents the final expressions for the width and shift of the Doppler Spectrum of microwaves reflected by the sea surface during bistatic sensing in the case of a moving receiver and a transmitter. An important feature of the proposed approach is the consideration of the antennas patterns of the receiving and transmitting antennas. And it is taken into account that the antennas patterns of the receiver and transmitter can be different and asymmetrical. The correct choice and use of antennas with different patterns allows directly expressing the sea surface parameters of interest from the measured characteristics of the Doppler Spectrum.
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the Doppler Spectrum of the microwave radar signal backscattered by the sea surface at low incidence angles
International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Vladimir Karaev, Mariya Ryabkova, M A Panfilova, Yury Titchenko, E M MeshkovAbstract:Results of the first experiment on measuring the Doppler Spectrum of the microwave signal backscattered by the sea surface at low incidence angles (< 20°) made from a sea platform are presented. At small incidence angles (<10°), the reflection is quasi-specular and the Kirchhoff approximation is used to calculate the Doppler Spectrum. Comparison showed a good agreement between the experiment and numerical estimates of the Doppler Spectrum model. The measurements have shown that in the transition range of incidence angles (10°-20°), one should take into account the resonant scattering contribution to explain the features of the measured Doppler Spectrum. To calculate the Doppler Spectrum in the transition range, an advanced Bragg scattering model was used. It is shown that the employed quasi-specular and Bragg scattering mechanisms qualitatively explain the dependences of the width and shift of the Doppler Spectrum on the incidence angle. In passing to quantitative estimates, tilt modulation and hydrodynamic modulation of the Bragg scattering mechanism should be taken into account, which will be done in a future study. The first measurements of the dependences of the width and shift of the Doppler Spectrum on the incidence angle allow comparing well-known scattering models.
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IGARSS - The Doppler Spectrum of The Microwave Radar Signal Backscattered by the Sea Surface at Low Incidence Angles
IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018Co-Authors: Vladimir Karaev, Mariya Ryabkova, M A Panfilova, Yury Titchenko, E M MeshkovAbstract:Results of the first experiment on measuring the Doppler Spectrum of the microwave signal backscattered by the sea surface at low incidence angles (< 20°) made from a sea platform are presented. At small incidence angles (
