Comparison of different methods for reconstruction of microwave holograms recorded by the subsurface radar

A family of holographic subsurface radars, named RASCAN, has been produced during more than fifteen years. Until recently RASCAN radar had the direct-gain receiver that was registering amplitude of reflected signal only. Therefore, the obtained images were used without any processing. New generation of RASCAN radars with quadrature receiver allows recording two quadratures of reflected signal and finding its amplitude and phase. The performance of such devices crucially depends on the frequency bandwidth of sounding signal and on the appropriate reconstruction algorithms. The goal of this paper is to discuss the basics of various approaches such as single-frequency, two-frequency and wide-band. The comparison of the methods was carried out on the simulated and experiment holograms.