The Scattering Coefficient for Shore-to-Air Bistatic High Frequency (HF) Radar Configurations as Applied to Ocean Observations

Chen, Zezong; Li, Jian; Zhao, Chen; Ding, Fan; Chen, Xi

doi:10.3390/rs11242978

Cited by 4 publications

(6 citation statements)

References 38 publications

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“…Here the Stratton-Chu integral is employed to calculate the scattered field in the far zone of the scattering patch [12,32]. For monostatic configuration, substituting the scattered field from the rough part of the scattering patch into the Stratton-Chu integral gives (26), which represents the scattered field H f (R 0 , t) at the receive antenna.…”

Section: The Scattered Field Far From the Scattering Patchmentioning

confidence: 99%

“…In (26), H sr denotes the magnetic field corresponding to E sr ; k s = (−k 0 sin θ i , 0, k 0 cos θ i ) is the wave vector of the scatterd field; the square area {…”

Section: The Scattered Field Far From the Scattering Patchmentioning

confidence: 99%

“…Anderson [24] proposed the airborne passive HF radar which can be used to monitor the sea. Later, Chen et al [25,26] theoretically analyzed the sea echoes of the shore-to-air bistatic HF radar. Meanwhile, Voronovich and Zavorotny [27] proved the possibility of extracting the wave height spectrum using airborne HF/VHF radars.…”

Section: Introductionmentioning

confidence: 99%

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Sea Echoes for Airborne HF/VHF Radar: Mathematical Model and Simulation

et al. 2020

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Currently, shore-based HF radars are widely used for coastal observations, and airborne radars are utilized for monitoring the ocean with a relatively large coverage offshore. In order to take the advantage of airborne radars, the theoretical mechanism of airborne HF/VHF radar for ocean surface observation has been studied in this paper. First, we describe the ocean surface wave height with the linear and nonlinear parts in a reasonable mathematical form and adopt the small perturbation method (SPM) to compute the HF/VHF radio scattered field induced by the sea surface. Second, the normalized radar cross section (NRCS) of the ocean surface is derived by tackling the field scattered from the random sea as a stochastic process. Third, the NRCS is simulated using the SPM under different sea states, at various radar operating frequencies and incident angles, and then the influences of these factors on radar sea echoes are investigated. At last, a comparison of NRCS using the SPM and the generalized function method (GFM) is done and analyzed. The mathematical model links the sea echoes and the ocean wave height spectrum, and it also offers a theoretical basis for designing a potential airborne HF/VHF radar for ocean surface remote sensing.

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Section: The Scattered Field Far From the Scattering Patchmentioning

confidence: 99%

“…In (26), H sr denotes the magnetic field corresponding to E sr ; k s = (−k 0 sin θ i , 0, k 0 cos θ i ) is the wave vector of the scatterd field; the square area {…”

Section: The Scattered Field Far From the Scattering Patchmentioning

confidence: 99%

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Sea Echoes for Airborne HF/VHF Radar: Mathematical Model and Simulation

et al. 2020

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“…The derivation of Johnstone appears to have an error which causes the difference in the resulting expressions; Gill and Walsh followed a more complicated method, however, it has been shown that the monostatic form of their radar cross section is similar to Barrick's and it is, therefore, unnecessary to change the existing operational inversion programs to use theirs instead. Another recent derivation is given in Chen et al [23].…”

Section: Introductionmentioning

confidence: 99%

Measuring the Directional Ocean Spectrum from Simulated Bistatic HF Radar Data

2020

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HF radars are becoming important components of coastal operational monitoring systems particularly for currents and mostly using monostatic radar systems where the transmit and receive antennas are colocated. A bistatic configuration, where the transmit antenna is separated from the receive antennas, offers some advantages and has been used for current measurement. Currents are measured using the Doppler shift from ocean waves which are Bragg-matched to the radio signal. Obtaining a wave measurement is more complicated. In this paper, the theoretical basis for bistatic wave measurement with a phased-array HF radar is reviewed and clarified. Simulations of monostatic and bistatic radar data have been made using wave models and wave spectral data. The Seaview monostatic inversion method for waves, currents and winds has been modified to allow for a bistatic configuration and has been applied to the simulated data for two receive sites. Comparisons of current and wave parameters and of wave spectra are presented. The results are encouraging, although the monostatic results are more accurate. Large bistatic angles seem to reduce the accuracy of the derived oceanographic measurements, although directional spectra match well over most of the frequency range.

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“…From this discovery, the first-order and second-order Doppler models based on a small perturbation method were established by [6][7][8]. Chen et al [9] analyzed the simulated echo Doppler spectra for various parameters based on a shore-to-air bistatic HF radar model. Subsequently, more investigations focused on microwave bands.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Modeling of Doppler Spectra for Offshore UHF-Band Sea Clutter at Low Grazing Angles

Zhao,

Wu,

Zhang

et al. 2023

JMSE

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The Doppler spectra of sea echoes, which contain abundant information on floating scatterers, are important for exploring the characteristics of sea clutter. Using sea clutter data at low grazing angles observed by a coherent ultra-high frequency (UHF) radar located on Lingshan Island in the Yellow Sea, China, this study conducted detailed research on the characteristics of Doppler spectra with multiple ocean parameters, including grazing angle, significant wave height (SWH), and wave directions. The effect of sea echoes with different local normalized intensities on short-time Doppler spectra was further studied. The results indicate that with increasing sea states, the bimodal behavior of Doppler spectra, an evident phenomenon of Bragg scattering, gradually weakens. The frequency shifts of the mean spectra increased linearly with increasing SWH and wind speed, decreased linearly with increasing grazing angle, and decreased with the cosine value of the relative wave direction angles. In comparison, frequency shifts of the short-time spectra increased with increasing sea states and local echo intensities but fluctuated around a fixed value after reaching a certain extent. For spectral widths, the grazing angle is a significant influencing factor, with its broadening trend evident with a decrease in the grazing angle, whereas other ocean parameters, such as wave direction and wind direction, have no apparent influence. Considering the major contributions of the parameters, semi-empirical models for the mean spectral frequency shifts, mean spectral widths and short-time spectral frequency shifts were proposed. By verifying the measured data and predicted results, the models exhibited good prediction accuracy and applicability. The proposed inferences and models are helpful for understanding low grazing angle UHF-band sea clutter characteristics and improving target detection algorithms in offshore areas. These findings supplement previous studies on sea clutter Doppler spectra.

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The Scattering Coefficient for Shore-to-Air Bistatic High Frequency (HF) Radar Configurations as Applied to Ocean Observations

Cited by 4 publications

References 38 publications

Sea Echoes for Airborne HF/VHF Radar: Mathematical Model and Simulation

Sea Echoes for Airborne HF/VHF Radar: Mathematical Model and Simulation

Measuring the Directional Ocean Spectrum from Simulated Bistatic HF Radar Data

Characterization and Modeling of Doppler Spectra for Offshore UHF-Band Sea Clutter at Low Grazing Angles

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