INNOVATIVE FRACTAL-BASED MODELS FOR RADAR ALTIMETER DATA

An innovative electromagnetic model for the radar echoes received by a microwave altimeter is proposed: it is based on fractal models employed both to describe the natural surface and to evaluate the surface scattering behaviour. The scattering surface is modelled by means of the fractional Brownian model (fBm) process, whose realizations are obtained by using the band-limited Weierstrass-Mandelbrot (WM) function. The scattering process is evaluated by means of the Physical Optics solution specifically derived for fractal surfaces. Rationale to apply this solution to the evaluation (in time domain) of the received echoes is provided. Dependence of the return pulse shapes on surface topography at different roughness scales is highlighted: some relevant meaningful examples are presented. Simulation results are provided to show the potential of the proposed technique that could be the fundamental element to generate an atlas of expected returns from a given radar altimeter.