A Technique for Including Edge Diffraction Effects on RCS Evaluation at Fresnel Region Ranges

The aim of this paper is to propose a simple and low-cost technique to measure the RCS of a complex target in the Fresnel region and in a multipath environment. The diffracted field by the target is calculated using a method based on equivalent currents. The reflected field is computed using the physical optics approach and the tangent plane approximation. The ratio between the analytical expression of the radar cross section in the far-field and Fresnel region results in a field-zone extrapolation factor for the diffracted field. The RCS resulting from the scattering parameters measured at Fresnel region distances is then corrected with that field-zone extrapolation factor. The method was validated by simulations and measurements on a rectangular, metallic target.