In High-Frequency Surface Wave Radar applications (HFSWR), targets at close range are often masked by very strong sea clutter returns in the range-Doppler spectrum. The clutter is highly non-homogeneous in the Doppler dimension, presenting two peaks at resonance Doppler frequencies, referred to as Bragg lines, and several smaller side peaks. Due to this complex scattering mechanism, a Gaussian assumption for clutter returns does not hold, and several works propose modeling sea clutter returns in HF range-Doppler spectra as a Weibull distribution. This work presents an analysis of the performance of a cell-averaging constant false alarm rate (CA-CFAR) algorithm designed for Weibull-distributed clutter. A closed-form probability of detection of the Weibull CACFAR is compared to a numerical simulation of sea clutter based on a physical model of sea radar cross-section (RCS). The clutter model takes into consideration wind conditions, as well as the operating parameters of the radar. It is demonstrated through numerical simulation of the physical model that the clutter echo distribution, depending on the sampling position in the range-Doppler spectrum and proximity to a Bragg line, can take the form of an exponential or a Rayleigh distribution. Thus, the overall distribution of clutter returns can be represented by a Weibull model. Results indicate that the closed-form analytical expression act as an upper bound for detector performance, that is, in practice, degraded by the strong peaks of the clutter power.
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