GPR is a non-destructive technique that consists in the emission of high frequency electromagnetic waves through a medium. Different electromagnetic properties and discontinuities within the medium produce reflections that allow to characterize its internal structure. In particular, pulses of radar energy are generated from a dipole transmitting antenna, placed on, or near, the surface of the medium under investigation: from soil layering, to masonry wall, up to frescoes (Leucci 2019; Masini et al. 2007; Masini et al. 2017).
Focusing on architectural heritage applications, the measure of the time elapsed between transmission, reflection off a discontinuity and reception back at a surface radar antenna along with suitable data processing procedures, allow to identify and locate reflectors that, suitably post processed and visualized in 3D, enable to provide important information on the masonry, such as presence of cracks and fractures, the internal composition, the connection characteristics between stone blocks (Leucci et al. 2011).
Such approach has been applied for the characterization of the columns of the Convento do Carmo church, in Lisbon.