The aim of this study is to present a technique for object geometry retrieval using scattered field information based on phaseless acquisition, so that a scanning system can be implemented without the need of an expensive vector network analyser. The inverse scattering is accomplished through a two-step strategy that is powered thanks to the combination of the scattered signal with a synthesised reference wave. Thus, the phase is firstly recovered by considering the spectral properties of the mixed signal. Secondly, the reflectivity of the object is computed by means of an inverse scattering algorithm accelerated by a multipolar expansion. The technique is applied and validated for planar as well as spherical ranges considering simulated as well as measured data.