Spatial domain indirect holographic technique for antenna near-field phaseless measurements

A spatial domain formulation of an indirect holographic technique, useful for antenna near-field phase retrieval, is presented in this paper. The proposed approach is based on the adoption of three synthetic reference signals, giving three sets of amplitude-only near-field data. These are directly processed in the spatial domain to accurately retrieve the near-field phase, from which the antenna radiation features can be subsequently computed. Despite the standard indirect holographic approach, no data processing is required in the spectral (Fourier transform) domain, thus completely avoiding the problem of spectrum overlapping which limits the accuracy of standard method. The effectiveness of the proposed technique is demonstrated by a numerical test on a linear dipole array, as well as by experimental results on a ridged-horn antenna.