Microwave imaging of buried objects for ground radar tomography

The detection and identification of buried inhomogeneities using electromag netic waves are of great importance for nondestructive testing in geophysic al, civil engineering, military, or humanitarian applications. The approach described here uses a linear inversion algorithm based on diffraction tomo graphy to process the backscattered field signal generated by the buried in homogeneities, measured over a probing area, for computation of a tomograph ic image of the ground. The technique has been extended to cater for time p ulse (synthetic pulse or real pulse) illumination and to incorporate the ne ar-field radiation pattern transmitted by a broadband antenna. The backscat tered field is measured at various locations with a receiving antenna for d ifferent positions of the transmitting antenna. The main advantages of such a method are the use of explicit formulas for solving the imaging problem and the possibility of rapid image display thanks to the use of Fast Fourie r transform to implement the reconstruction algorithms on PCs. First, a num ber of tomographic reconstructions of buried objects are given for situatio ns of practical interest. Results of numerical simulations with a Rayleigh incident pulse in the frequency band [0.3,3.0] GHz and the use of a bow tie antenna in the frequency band [0.3,1.3] GHz are presented. Second, tomogra phic reconstructions of buried objects are presented and discussed, to demo nstrate the influence of object dielectric properties versus soil electroma gnetic parameters.