Modelling of the electromagnetic scattering by sea surfaces at grazing incidence. Application to HF surface wave radars

Abstract

Propagation and remote sensing / Propagation et télédétection Modelling of the electromagnetic scattering by sea surfaces at grazing incidence. Application to HF surface wave radars Modélisation la diffusion électromagnétique en incidence rasante par des surfaces océaniques. Application aux radars hautes fréquences à ondes de surface

Method for the Sea Clutter Characterization in HF Surface Wave Radars From the Fields Diffracted by the Sea Surface

“…The sea surface height follows a Jonswap spectrum [28] with wind direction θ 0 = 10°and Beaufort scale 4 with The size of the surface was chosen by considering that it must be large enough to be statistically representative of the sea state. This means that two different realizations of the sea surface must be similar from a statistical point of view [27]. Intuitively a surface with size of some wavelengths is needed.…”

“…This size corresponds to a region of strong correlation. To ensure the statistical representativeness of the sea surface, an analysis of two characteristic statistical properties of a rough surface is done in [27]. These properties are the correlation length (L c ) and the mean square height (h rms ).…”

“…The system parameters that mainly affect the value of the fields on the Huygens surface are the following: 1) Frequency of the wave: It affects both diffracted and incident fields. 2) Sea state: specified, for example, in the Beaufort scale [27], it affects only the diffracted fields. 3) Angle of the incoming trajectory: It affects the diffracted fields.…”

“…The distance between each antenna and the origin is 500 m. The transmitting antenna is located at an azimuth angle of φ i , while the azimuth angle of the receiving antenna is −φ i . A perfect electric ground plane covers the entire region under the monopoles and the patch so that, in the simulation, the patch and its image are considered [27].…”

“…The amplitude A of the sinusoidal surface in (1) is chosen to be 2.0125 m to represent the significant height of the sea state given by the scale 5 of Beaufort [27]. The constant level of 3A/2 is added in (1) to make all height values positive.…”