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Formulation and application of a physics-based model for the amplitude distribution of bistatic sea clutter

Balakhder, Ahmed Mohammed
http://rave.ohiolink.edu/etdc/view?acc_num=osu1587696646072952

Abstract Details

2020, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
The study of signal returns or scattered field from sea surface has become a topic of interest over the past several decades. For some remote sensing applications, scattered fields from sea surface might be the purpose to study waves, currents, wind speed, wind direction, and so no. In many other applications for navigation or surveillance, returns from the sea surface are unwanted signals, also referred to as sea clutter. The performance evaluation of maritime radar detection in the presence of sea clutter remains a challenging problem in radar systems analysis. Detection of a target in sea clutter requires a detailed understanding of sea clutter statistics. In particular, the amplitude distribution function for sea clutter is important for designing target detection algorithms and also for assessing the utility of varying bistatic geometries in target detection applications. Various amplitude distribution models for sea clutter have been developed through empirical fits. This thesis investigates the potential of the amplitude distribution of bistatic sea clutter using a physics-based model. The formulation of the model is based on a ``two-scale'' decomposition and the unified Elfouhaily spectrum. The small scale roughness in the model represents the scatters within the facet, where the facet size is the radar range resolution. Scattering from small scale roughness is computed using the second-order Small Scale Approximation. The large scale roughness causes the tilting of the facet by slopes, which are Gaussian distributed with zero mean and appropriate mean square slopes produced by the ``long wave'' portion of the spectrum. This model provides a physical basis of the mean power (texture) function in the compound Gaussian model. The model developed in this thesis does not include sea surface features such as breaking waves, so that the ``sea spike'' behaviors of sea clutter important at lower grazing angles are not captured. The model is therefore limited to applications at larger grazing angles but otherwise throughout the entire bistatic scattering hemisphere. Two approaches are proposed to compute the amplitude distribution using the two-scale decomposition, namely, Monte Carlo simulation and analytical integration. The study of the amplitude distribution of the simulated sea surface as a function of frequency, polarization, and the bistatic configuration is considered, and comparisons are made with the theoretical amplitude distribution, which indicates appropriate choices of the mathematical representation to model the bistatic sea clutter. Based on the mathematical representation of the bistatic sea clutter, fundamental detection analysis of a fixed target is studied. The two-scale model is also used to compare with measured bistatic sea clutter data. The study of the coherency properties of specular scattering from ocean surfaces using approximate models of coherent and incoherent contributions is considered. These models are described as a function of observation geometry, frequency, bandwidth, and surface properties. The Elfouhaily spectrum is used to consider sea surface statistical properties such as RMS height for the coherent power and slope variances for incoherent power.
Joel Johnson (Advisor)
Robert Burkholder (Committee Member)
Fernando Teixeira (Committee Member)
138 p.
Electrical Engineering

Recommended Citations

Citations

  • Balakhder, A. M. (2020). Formulation and application of a physics-based model for the amplitude distribution of bistatic sea clutter [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587696646072952

    APA Style (7th edition)

  • Balakhder, Ahmed. Formulation and application of a physics-based model for the amplitude distribution of bistatic sea clutter. 2020. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1587696646072952.

    MLA Style (8th edition)

  • Balakhder, Ahmed. "Formulation and application of a physics-based model for the amplitude distribution of bistatic sea clutter." Doctoral dissertation, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587696646072952

    Chicago Manual of Style (17th edition)

osu1587696646072952
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