Electromagnetic Wave Scattering in Dense Media: Applications in the Remote Sensing of Sea Ice and Vegetation

Backscattering Analysis Utilizing Relaxed Hierarchical Equivalent Source Algorithm (RHESA) for Scatterers in Vegetation Medium

“…In Figure 4, the incident angle was fixed at 20 de where p and q are the scattered and incident polarization, respectively, and fpq is the scattering amplitude of the scatterer. The detailed formulation of fpq with amplitude and Fresnel phase correction term were derived, and are available in [3,5] for cylindrical scatterer, and in [10,11] for elliptical disk scatterer.…”

“…In [3,5], amplitude and Fresnel phase correction terms were added in the scattered field terms of spheres, circular disks, needles, and cylinders, in order to account for the close distance of the scatterers, and their backscattering cross sections were studied. In [10,11], scattered field terms with Fresnel corrections were derived for general ellipsoids and elliptic disks, based on the generalized Rayleigh-Gans approximation. The backscattering return from the layers of dense media was then modelled using the radiative transfer equation, which was solved iteratively up to the second order to calculate the multiple scattering effect.…”

“…The background was considered to be free space. In [3,5,10,11], the backscattering cross section of the scatterer was calculated using the following formula: In [3,5,10,11], the backscattering cross section of the scatterer was calculated using the following formula:…”

“…Theoretical models in microwave remote sensing research have been developed using analytical methods that employ approximation models [1][2][3][4][5][6][7][8][9][10][11][12], especially for vegetation media [9][10][11][12]. Analytical method models can provide some physical insight into media, and allow the study of scattering behaviour for variations in parameters; however, their accuracy is limited, as this is carried out by approximating the scatterers into limited shapes such as spheres, cylinders, needles, ellipsoids, and elliptic discs.…”

“…In order to achieve that, an important step is to use RHESA in modelling the basic shapes of scatterers in vegetation to compare its backscattering cross section with previous studies that used approximation models. In this study, backscattering analyses for volume scattering for a single cylinder and an elliptic disc-shaped scatterer were performed using RHESA, and compared with the results in [3,5,10,11]. This is carried out to study the prospect of utilising RHESA for volume scattering on a larger scale for vegetation media in the future, as cylinders and elliptic discs are the most common shapes in the vegetation area (representing stems, branches, trunks, and leaves); moreover, their scattering patterns are already available in the literature for comparison and validation purposes.…”