Comparison of echo suppression techniques in near field antenna measurement applications

This paper reports the findings of a comparative investigation of two versatile echo suppression techniques applicable to general antenna near field measurement scenarios with echoes of unknown origin. Both techniques are based on spatial filtering of the measured field taking advantage of the apriori knowledge of the antenna size and can be applied to near field measurements in any canonical scan configuration. The first technique takes advantages of the spatial filtering properties of the spherical waves expansion of the measured field. The second method is based on the reconstruction of equivalent currents and implements the spatial filtering as a direct consequence of the selected size and shape of the reconstruction surface. The benefit of using redundant data in both techniques as a mean to achieve further echo reduction in spherical near field scan geometry is examined with particular attention. The investigation has been accomplished with measured data on a SATIMO wideband horn using different sampling of the full sphere.