Far-field measurements and maximum entropy analysis of lossy material on a conducting plate

The relationships between Fourier techniques and maximum entropy techniques for the case of scattering measurements from metal-plate-backed lossy dielectric material are described. A set of experimental measurements were made in the frequency and aspect-angle domains on square panels of a multilayer radar absorbing material (RAM) backed by a conducting plate (approximately 30×30 cm). The minimum scattered signal was observed in the 9-12-GHz band. Experiments were performed over a band of frequencies from 2 to 18 GHz. Analysis techniques are described for transformations to the time and Doppler (cross-range) domains. Interpretations of the results with respect to the penetration of the radar signal into the RAM and scattering from the edge discontinuity of the plate are given and discussed