The authors concentrate on the ripples in the reflected plane wave created by edge diffractions. It has been shown that the ripples have to be smaller than 0.1 dB to make accurate radar cross-section measurements. It is found that tapering the incident field that illuminates the parabolic reflector in such a fashion that the edges are illuminated at a reduced level results in slope-diffracted fields that are proportional to the spatial variation in the field. Care should therefore be taken to control the taper and resulting slope-diffracted fields as these fields can lead to severe ripples in the target zone.
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