Radar reflection from surfaces with ruptures

In some radar earth observation problems, it is necessary to investigate reflections from structures with internal ruptures such as fractures in ice ravines or all kinds of hollow spaces. Polarimetric radar may sense the structure of ruptures by doing measurements under different observation angles. Experimental data show that the reflection coefficient may have a significant magnitude. Pit walls which deviate from fully parallel walls can also cause this effect. Analysis based on models therefore must always be extended very carefully. In this paper, models for structures with internal ruptures in the form of a wedge-shaped fracture are proposed. In general, the radar senses the structure with a rupture under a specific angle using an antenna with a given antenna pattern. Relationships between the reflection coefficient at observation angle θ, the geometrical dimensions and the electrophysical parameters of the pit must then be determined. Strictly speaking, diffraction theory is needed to solve such problems. However, if we assume that the dimensions of the pit are much larger than the wavelength, geometrical-optics approximations turn out to be very fruitful. Numerical results are shown