scholarly journals Ocean Surface Cross Section for Bistatic HF Radar Incorporating a Six DOF Oscillation Motion Model

2019 ◽  
Vol 11 (23) ◽  
pp. 2738 ◽  
Author(s):  
Yao ◽  
Xie ◽  
Huang
Keyword(s):  
Cross Sections ◽  
Ocean Surface ◽  
Second Order ◽  
Hf Radar ◽  
Motion Model ◽  
Floating Platform ◽  
Platform Motion ◽  
First Order ◽  
Order Spectrum ◽  
Six Dof

To investigate the characteristics of sea clutter, based on ocean surface electromagnetic scattering theory, the first- and second-order ocean surface scattering cross sections for bistatic high-frequency (HF) radar incorporating a multi-frequency six degree-of-freedom (DOF) oscillation motion model are mathematically derived. The derived radar cross sections (RCSs) can be reduced to the floating platform based monostatic case or onshore bistatic case for corresponding geometry setting. Simulation results show that the six DOF oscillation motion will result in more additional peaks in the radar Doppler spectra and the amplitudes and frequencies of these motion-induced peaks are decided by the amplitudes and frequencies of the oscillation motion. The effect of the platform motion on the first-order radar spectrum is greater than that of the second-order, and the motion-induced peaks in the first-order spectrum may overlap with the second-order spectrum. Furthermore, yaw is the dominant factor affecting the radar spectra, especially the second-order. Moreover, the effect of platform motion on radar spectra and the amplitudes of the second-order spectrum decreases as the bistatic angle increases. In addition, it should be noted that the amplitudes of the Bragg peaks may be lower than those of the motion-induced peaks due to the low frequency (LF) oscillation motion of the floating platform, which is an important finding for the applications of the floating platform based bistatic HF radar in moving target detection and ocean surface dynamics parameter estimation.

scholarly journals Bistatic High Frequency Radar Ocean Surface Cross Section for an FMCW Source with an Antenna on a Floating Platform

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yue Ma ◽  
Weimin Huang ◽  
Eric W. Gill
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
High Frequency ◽  
Continuous Wave ◽  
Ocean Surface ◽  
Radar Cross Section ◽  
Second Order ◽  
Floating Platform ◽  
High Frequency Radar ◽  
Radar Cross Sections

The first- and second-order bistatic high frequency radar cross sections of the ocean surface with an antenna on a floating platform are derived for a frequency-modulated continuous wave (FMCW) source. Based on previous work, the derivation begins with the general bistatic electric field in the frequency domain for the case of a floating antenna. Demodulation and range transformation are used to obtain the range information, distinguishing the process from that used for a pulsed radar. After Fourier-transforming the autocorrelation and comparing the result with the radar range equation, the radar cross sections are derived. The new first- and second-order antenna-motion-incorporated bistatic radar cross section models for an FMCW source are simulated and compared with those for a pulsed source. Results show that, for the same radar operating parameters, the first-order radar cross section for the FMCW waveform is a little lower than that for a pulsed source. The second-order radar cross section for the FMCW waveform reduces to that for the pulsed waveform when the scattering patch limit approaches infinity. The effect of platform motion on the radar cross sections for an FMCW waveform is investigated for a variety of sea states and operating frequencies and, in general, is found to be similar to that for a pulsed waveform.

Second-order Raman spectrum of ZnSe

1970 ◽  
Vol 48 (21) ◽  
pp. 2499-2506 ◽  
Author(s):  
J. C. Irwin ◽  
J. LaCombe
Keyword(s):  
Raman Spectrum ◽  
Theoretical Model ◽  
Second Order ◽  
Optical Phonons ◽  
Zone Boundary ◽  
Sum Rule ◽  
First Order ◽  
Zinc Blende ◽  
Order Spectrum ◽  
Phonon Spectra

The first- and second-order Raman spectra of ZnSe have been measured and an interpretation of the spectra has been carried out. The first-order spectrum yielded the values [Formula: see text] and [Formula: see text] for the longitudinal and transverse optical phonons at the center of the Brillouin zone. The zone boundary frequencies at the critical points X, L, and W have been estimated from the second-order spectrum. These frequencies were chosen to be consistent with both the experimental results and a theoretical model. The resulting values were further checked for consistency with a sum rule and by using regularities observed previously in the phonon spectra of zinc blende semiconductors.

Airy minima in 4He +28Si elastic and inelastic scattering

2020 ◽  
Vol 35 (19) ◽  
pp. 2050159
Author(s):  
Yu. A. Berezhnoy ◽  
A. S. Molev
Keyword(s):  
Elastic Scattering ◽  
Inelastic Scattering ◽  
Energy Dependence ◽  
Cross Sections ◽  
Differential Cross ◽  
Second Order ◽  
Differential Cross Sections ◽  
First Order ◽  
Elastic And Inelastic Scattering ◽  
Matrix Description

We present the results of the [Formula: see text]-matrix description of the [Formula: see text] elastic and inelastic scattering differential cross-sections between 40 and 240 MeV with allocation of Airy minima of various orders. The first-order Airy minima have been unambiguously identified in the differential cross-sections for elastic scattering and inelastic scattering to the first [Formula: see text] state of [Formula: see text] at energies [Formula: see text] MeV, and the second-order Airy minima — at [Formula: see text] MeV. The angular positions of these minima obey an inverse dependence on energy. The intensities of nuclear refraction and absorption also obey the same energy dependence.

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