This paper presents an interferometric algorithm capable of working with SAR images obtained from measurements carried out with antennas that describe a circular trajectory. The antennas are positioned on a vertical mast at a low height. Therefore, the system is very interesting for surface scattering studies and buried objects detection due to the very high spatial resolution that C-SAR (Circular SAR) images present. A summary of the analytical formulation of the C-SAR processor and a complete description of the interferometric algorithm are presented along. Some experimental results obtained in anechoic chamber are also shown.